Parasites: A Treatise on the Entozoa of Man and Animals / Including Some Account of the Ectozoa

by T. Spencer Cobbold

Part IX (Solidungula).

It will naturally be expected that I should give a full account of the parasites of the solipedal, solidungulate, or equine mammals. As regards the horse I regret that I cannot meet this expectation in so complete a manner as the subject deserves; nevertheless, with the aid of an extended bibliography the summary here offered will be found to be tolerably exhaustive. At all events I think I may say that no similar record has hitherto been attempted.

The liver fluke (Fasciola hepatica), though not very frequent in the horse, is not uncommon in the ass. In dissecting-room subjects at the Royal Veterinary College it is often encountered. In France it was originally found in the horse by Daubenton. As I learn from Sonsino, Dr Abbate Bey recently recorded a similar find at Cairo. In solipeds generally the liver fluke appears to be almost harmless, for, notwithstanding the frightful ravages produced by rot amongst a variety of animals besides sheep, we have no evidence of the destruction of horses from this cause. In the German outbreak of 1663–65 multitudes of cattle and deer perished, and in the French outbreak of 1829–30 five thousand horned beasts succumbed in the arrondissement of Montmédy alone. In neither of these epizoötics were the solipeds affected. More importance attaches itself to the study of the amphistomatoid flukes. These parasites, though in a scientific sense only recently discovered in equine bearers, have been long known to the natives of India. They appear to be capable of producing serious intestinal irritation. I have described two forms (Amphistoma Collinsii and A. Coll., var. Stanleyi), which infest the colon. The specimens sent to Prof. Simonds from India by Mr Stanley, V.S., were much larger than those sent to me from Simla by Mr Collins, V.S., some ten years later (1875). As in all other amphistomes obtained from the intestines of elephants and cattle, the worms, when fresh, were of a bright brick-red color. By the natives of India these parasites are called Masuri; but no description of the worms had been published prior to the account which I gave of the contributions forwarded by Major-General Hawkes, Mr Collins, and Mr Stanley.

I shall have occasion to speak of the elephant’s Masuri further on; but in the meantime I must remark that the generally received notion as to the parasitic cause of the earth-eating propensities of various animals seems to have some foundation in fact. Not alone from Major-General Hawkes in Madras, from Mr Folkard in Ceylon, and from various other trustworthy sources, have I been informed of this habit on the part of Indian horses, but Dr Rowe told me that Australian horses, and even sheep, infested with stomach-worms, are in the constant habit of consuming large quantities of sand. From all the facts that have come before me, I am inclined to think that gastric or intestinal irritation, however brought about, may induce the habit in question, parasites being only one of the many sources of irritation giving rise to symptoms of colic in solipeds and pachyderms alike. At all events the African elephants at the London Zoological Society’s Menagerie, as repeatedly witnessed by myself, are in the habit of swallowing large quantities of soft mud during the summer months, but no traces of masuri have as yet been detected in their fæces.

When by letter I informed Major-General Hawkes of an interesting find by Mr Collins of about a thousand Amphistomes in the colon of a horse that had died at Simla, the announcement called forth a reply which is sufficiently instructive to be quoted. Writing from Secunderabad in July, 1875, he says, respecting this “find:”—“Your statement has incidentally thrown light upon a subject which has puzzled many of us in this country. It occasionally happens that a horse, on being opened after death, is found to have accumulated in his intestines large quantities of sand and gravel. In a recent case this accumulation amounted to 141/2 lbs. Until recently it was always held that this gravel or sand could only be introduced with the animal’s food. All grain in this country is trodden out by bullocks on an earthen floor, and the grain undoubtedly contains a proportion of sand and gravel derived from this source. Although this ought to be carefully washed out before it is given to the horse, still, owing to the carelessness of the native horse-keepers, this cleaning is, I expect, often omitted. In the daily ‘feed’ of eight or ten pounds of grain given to each horse the utmost quantity of sand or gravel that could be found admixed therewith would not probably exceed two or three ounces; consequently it would take from 77 to 116 days to accumulate so large a quantity as 141/2 lbs. Now, the advocates of the theory of the gradual accumulation of sand in this way have never been able to explain why the grain, grass, hay, and other ingesta should pass in the ordinary way through the intestines, whilst this sand or gravel remains behind. One can understand the possibility of such substances as wool, hair, or similar matters concreting in the alimentary canal, though I believe they are usually found in the stomach, and not in the intestines; but how a most incohesive substance like sand can possibly accumulate in the gradual way required by their theory I have never heard even plausibly explained. On the other hand, the fact that horses are often excessively addicted to eating earth is well known; and if my memory serves me correctly, it was found necessary, about twenty years ago, to remove the mud-walls of the pickets surrounding some of the horses of a mounted corps in this presidency in consequence of this habit. Now, given the fact that the amphistoma has been found in the horse (as your specimens prove), may we not fairly suppose it possible that the animal resorts to the same mode of ridding himself of this parasite as does the elephant? and also, would it not in a much more natural manner account for the large quantity of gravel or sand found in the intestines than does the theory of gradual accumulation? Reasoning from analogy, as in the case of the elephant, this eating of earth in the horse would be an instinctive effort on the part of the “host” to rid himself of the parasite. This self-taken remedy is doubtless in many cases quite effectual, though unnoticed. The fatal cases are probably those in which the horse has either overdone the remedy or where the system was too debilitated to carry off a quantity of sand or gravel that would otherwise have safely passed through the intestines of a horse in more robust health. The actual fact must, of course, be verified by careful investigation.”

Fig. 62.—Gastrodiscus Sonsinonis. a, Mouth; b, caudal sucker and posterior mesial cleft; c, left lip of the gastric disk; d, anterior mesial cleft; e, e. gas­tric sucker­lets; f, re­pro­duc­tive pa­pilla. En­larged. Orig­inal.

Closely allied to the Masuri is an amphistome which I originally named Gastrodiscus Sonsinoii, but which should be altered as opposite (Fig. 62). It exceeds 1/2″ in length and 1/3″ in breadth (16 mm. long by 10 broad). Its discovery by Dr Sonsino was one of the results of his examination of sixteen carcases of solipeds that died during the Egyptian plague of 1876. Specimens having been forwarded to Panceri, Von Siebold, Leuckart, and myself, most of us at once agreed that the worm was new to science. Pointing to the genera, Notocotylus and Aspidocotylus, I explained its close affinity to the latter more particularly. Whilst Notocotylus has fifty supplementary suckers on its back, Aspidocotylus has nearly two hundred small ventral suckers seated on a convex disk. In Gastrodiscus a still larger number of suckerlets are placed in the deep concavity of a large gastric disk formed by the outstretched and inrolled margins of the body of the parasite. Zoologically speaking, the odd thing about this singular worm lies in the circumstance that its nearest fluke-relation, so to speak (Aspidocotylus mutablis), dwells in a spiny-finned fish (Cataphractus); and this fish itself forms an aberrant genus of the family to which it belongs (Triglidæ). From what has been said it will be seen that our Gastrodiscus must not be confounded with Cotylegaster cochleariform (or with its synonym Aspidogaster cochleariformis), to which parasite Von Siebold was, I believe, induced to refer it. Like most of the true amphistomes, the worm in question infests the intestines. Although discovered by Sonsino at Zagazig in plague-affected corpses, there is no reason to suppose that this helminth was in any way etiologically connected with the Egyptian epizoöty.

The tapeworms of the horse are of great interest practically. Excluding Sander’s Tænia zebræ, which was doubtless T. plicata, at least five species have been described, but they may probably be all reduced to two distinct forms and their varieties. Whilst Tænia plicata acquires a length of three feet, the strobile of T. perfoliata never exceeds five inches. The lobes at the base of the head in the latter are distinctive. The former is usually confined to the small intestine, but the perfoliate worm often occupies the cæcum and colon in great numbers. As regards T. mamillana, I may say that neither Gurlt’s descriptions nor his figures are convincing. The worm is, I believe, identical with T. perfoliata. In like manner, after going into the matter with some care, I am accustomed to speak of Mégnin’s T. inerme as T. perfoliata, var. Mégnini, and of Baillet’s T. innomé as T. perfoliata, var. Bailletii. I have examined great numbers of equine tapeworms, but whether my determinations on this point are correct or not, the case recorded by Mégnin is of remarkable interest. Clinically, indeed, it is not entirely unique, since a somewhat similar case has been recorded by Mr Poulton. In Mégnin’s equine patient the autopsy revealed the presence of 200 bots, 153 lumbricoids, upwards of 400 oxyurides, and several thousand palisade worms, besides numerous tapeworms. In Mr Poulton’s patient large quantities of tapeworms were found in the duodenum (and in large sacs of the walls of other sections of the small intestine), and also myriads of the little four-spined strongyle, in addition to about a score of palisade worms. Both Mégnin’s and Poulton’s patients died suddenly; but the great interest attaching to Mégnin’s case arises from the boldness of manner in which the French savant interprets the phenomena of the intestinal sacculation in relation to the development of the tapeworms. M. Mégnin assumes that the sacs are due to the formation of polycephalous or cœnuroid scolices. Without contradicting Mégnin’s ingenious interpretation of the phenomena in question, I may say that the difficulty I have in accepting his view arises from the circumstance of the rarity of the occurrence of these sacs. In Poulton’s case of Tænia perfoliata, the sacs were present, and they were productive of similar results; but in the scores of other recorded cases of sudden death from the same species of tapeworm (as published by Mr Rees Lloyd, and myself), the presence of such sac-formations is not once mentioned. To be sure, their presence may have been overlooked, but this is scarcely likely, seeing the great care taken by Mr Lloyd in conducting the autopsies. I cannot dwell upon the subject at greater length. The presence of so many sexually-immature strobiles, combined with the existence of the intestinal wall sacs, certainly does seem to point to the existence of cœnuroid bladder-worms, but until the existence of the polycephalous scolex be actually demonstrated one must be cautious in concluding “that the horse nourishes at the same time the strobila and scolex of the unarmed tapeworm.” Practically, we now know for certain that not only are tapeworms capable of producing a fatal issue in isolated cases, such as those recorded by Mégnin and Poulton, but that they may also be productive of disastrous epizoöty, as proved by Mr Lloyd in the case of Welsh mountain ponies.

In this connection I may perhaps be pardoned for saying that this discovery in 1875 was one of the practical results directly issuing from the publication of my ‘Manual’ in 1874. The attention of the veterinary profession having been called to the subject of parasitic epizoöty, Mr Lloyd was the first to make search for helminths amongst some few of the carcases of the hundred and more equine animals that perished in South Wales. Two totally distinct epizoötics prevailed. In the Beacons district tapeworms alone were the cause of death, whilst in the Deangunid district scores of animals perished from strongyles. In another district a hundred animals perished from tapeworms. These parasites I identified as examples of Strongylus tetracanthus and Tænia perfoliata. Taking all the helminthological facts together we have made a great advance both in hippopathology and equine epidemiology; and, as I observed at the time, the scepticism which not unnaturally still exists (in reference to entozoa as a frequent cause of death amongst animals, both wild and domesticated) will sooner or later be dispersed by that wider attention to the subject which our labors have invoked.

In relation to equine disease the facts brought forward are too important to be dismissed in a single paragraph. As two distinct kinds of parasitic epizoöty were discovered, the circumstances connected with their separate detection must be noticed at greater length. Further on, I shall again deal with the helminthiasis due to strongyles. It was on the 17th of April, 1874, that I received from Mr Lloyd, of Dowlais, Glamorganshire, a communication calling my attention to a fatal epizoötic affecting ponies. He supposed the outbreak to be due to parasites. On the following day I also received a parcel containing portions of the lower intestines, which had been removed from one of the diseased animals. The victim in question, a pony mare, had died on or about the 12th of April, at Llangunider, Breconshire. Mr Lloyd states in his letter that he “presumes” that the pony’s death was caused “by the presence of small worms,” examples of which he now forwarded for the purposes of identification and investigation. He also sent some equine tapeworms. Mr Lloyd had already inferred that his small worms were “strongyles;” and in regard to the tapeworms he says:—“This species of parasite has caused, or is supposed to have caused, the death of at least one hundred mountain ponies.” The investigation being immediately proceeded with, I may so far anticipate my record of the results obtained as to state at once that the facts observed by me confirmed Mr Lloyd’s suspicions—proving, beyond a doubt, that the pony above mentioned had succumbed to injuries inflicted by myriads of minute strongyles. Not only did I find the fæcal matter of the colon loaded with mature strongyles, but the walls of the intestine were also occupied with encysted and immature forms of the same nematode species. To such an extent had infection taken place, that I was enabled to count no less than thirty-nine strongyles within the space of the one fourth of a square inch. All parts of the sections of the colon under examination were almost equally invaded; so that, taking the average, I am clearly within the mark in saying that every square inch of the gut yielded at least one hundred parasites. The walls of the entire colon must therefore have been occupied by tens of thousands of these creatures, to say nothing of the scarcely less numerous examples lying free or lodged within the fæcal contents of the bowel.

In a second and more extended communication, sent in reply to inquiries as to the cestodes, Mr Lloyd (whose letter I have abridged) writes:—“I regret that I cannot give you very full particulars respecting the tapeworms. During the last twelve months mountain ponies grazing on the lower districts of Breconshire, which comprise some of the highest mountains in South Wales, have been dying in great numbers, from what the farmers indefinitely term inflammation. From what I have seen and heard, it appears that there are three causes of death, the tapeworm, the small worms (which I presumed were a kind of strongyle), and catarrhal disorders, such as have been common among horses of late. By far the greater number of deaths (from what I can glean) have been caused by the parasites. In the Ystradfellte or Penderin districts there has been no investigation, although the disease has reigned there for a longer period, about eighteen months, with (from what I have heard) a larger number of deaths than elsewhere; so I shall let these remain for the present, as I have not had an opportunity to see or hear anything authentic about them. In the Talybont district the cause appears to be the small worms (like those I sent). The owner of the animals said that a month ago, when he went to look after his ponies, they were appearing quite well, and looked as well as he could expect them at this season, but he was astonished to find some of them a fortnight ago looking very lean and wasting, and he thought that the weather was the cause of it, yet resolved to see them oftener; the next time he saw them one was dead, and knowing of the loss in the neighbourhood, and fearing he would be a sufferer, he sought aid, applying to me. When I arrived two days following two more were dead, and they presented an emaciated appearance. The post-mortem examination revealed a healthy condition of the whole of the intestines, save slight thickening of some parts of the colon and rectum, which contained, enclosed in the mucous membrane, in cysts or minute sacs, worms coiled upon themselves. Each cyst, containing one worm, was best seen by transmitted light. The colon was nearly full of fæcal matter, which contained thousands of parasites scarcely visible. The largest were very few in number, not exceeding an inch in length and barely one sixteenth in diameter at the middle portion. They somewhat tapered at both ends. The cæcum was half full of fluid fæces, containing no visible worms; the rectum, with fæces of natural consistence, the examination of which revealed only two or three evident worms; so that the examination of fæces of living animals giving results like this would not assist the diagnosis, unless suspected. Small intestines—these latter contained about a dozen bots, which were nearly free, but had pierced to the muscular coat. I should think they had participated in the disease. The right lung had been slightly congested; nothing else abnormal to be seen. Possibly congestion of lungs would arise from the distress when pained with worms, for the pony was found on its back with its head in a thicket—it had not appeared to have struggled—with its teeth firmly closed.

“Respecting the animals affected with Tænia, it is remarkable that, as a rule, they are in fair condition. The average time they appear to be troubled with the worms is two months, and the symptoms observed have been many. They are at first seen to be unable to keep up with the other ponies, extending the head and turning the upper lip up, rubbing the quarters, staring coat, suddenly appearing distracted, seizing turf in mouthfuls when being griped or pained, others running away as fast as they can go, or rolling and kicking on the ground for five or ten minutes, then walking away as if nothing had happened, if coming down a slope quickly almost sure to fall headlong, easier caught, not unfrequently coughing, groaning noise, appetite good, and, what is peculiar in some of them, lameness of one of the hind limbs, mostly the near hind leg, with slight knuckling over at fetlock.

“Post-mortem appearance.—Abdominal viscera normal, save rectum, which is in some places slightly congested; colon nearly full of fæces, no worms; cæcum, in which worms are alone found, is nearly full of fæcal matter of thicker consistence than usual, and nearly half made up of worms; stomach half full of partly digested food; heart and lungs healthy; Schneiderian membrane injected; mucous membrane of trachea and part of larger bronchiæ of a more or less livid colour (which may be owing to asphyxia); corner of tongue bitten off; mouth very close.

“Several animals were found at times lying dead together.

“Of the Tænia as many as three or four ponies, which some hours previous had been seen grazing unaffected, were found dead on the same spot; and this to my own knowledge, one farmer having lost ten.

“Of the small worms I have been told by a farmer that in his district one of his neighbours had lost twelve ponies.”

As I had partly misunderstood my informant’s original statement, Mr Lloyd, in a third communication, repeated the evidence, emphatically reminding me that “the ponies affected with tapeworms are in a district six or seven miles distant from those affected with strongyles. Those troubled with tapeworms are in good condition, as a rule, up to death; they are noticed to be troubled generally for two months previous to death, and may be seen at one hour grazing and apparently well, and dead or dying the next hour. As many as four have been found dead at the same spot. In this (the Beacons) district the tapeworms alone have been found and not a single strongyle. In the Deangunid district strongyles only have been found, such as I sent you. The ponies have been noticed ailing for three or four weeks, becoming rapidly emaciated and dying from exhaustion. In tapeworm-affected animals the cæcum is nearly half full of these parasites. The animals thus affected are on the red sandstone formation, whilst those affected with strongyles occur on the limestone formation—the latter affording the drier situation.”

Being on the teaching staff of the Royal Veterinary College I was particularly glad to have the authority of an experienced veterinary practitioner to testify to the injuriousness of Tænia perfoliata in the horse. Over and over again I had pointed out to the members of my class the desirability of examining the fæces of solipeds where obscure symptoms of intestinal irritation existed. Not only so; at the request of friends I wrote out prescriptions suitable for equine patients suffering from tapeworm. I felt the more indebted to Mr Lloyd, inasmuch as his practical views served to strengthen the propositions I had advanced in connection with internal parasites as a frequent cause of epizoötics. My views were criticised at the time with a vigour and warmth well worthy of those who are afraid of advancing epidemiological science too rapidly; but it seems that so far from my having overstepped the bounds of moderation in this matter I had, in reality, been too cautious. Certainly it can now no longer be said that “the symptoms created by tapeworms in the horse are of little or no consequence.” Here, therefore, I repeat, we have made a clear and rapid advance in our knowledge of helminthic disease; and from the impulse thus given to hippopathology it is only reasonable to look for still further advances in veterinary medicine. By-and-by, the scepticism which not unnaturally exists in reference to entozoa as a frequent cause of death amongst animals, will be dispersed by even yet clearer enunciations regarding the important part these parasites play in the destruction of our most valuable creatures.

Apart from the question incidentally raised by Mégnin as to their origin and mode of development, the presence of larval cestodes in horses cannot be passed over. The common hydatid (Echinococcus veterinorum), though not of frequent occurrence, is occasionally productive of fatal consequences. Very interesting cases are recorded by Messrs Henderson and Kirkman, aided by the valuable comments of Professor Varnell. Mr Hutchinson observed an hydatid in a horse’s eye, and Mr Vincent noticed lameness, as resulting from hydatids. But one of the most interesting cases of hydatids in solipeds is that described by Professor Huxley, from a zebra that died at the Zoological Gardens in 1852. As stated in Huxley’s elaborate memoir (freely quoted in the first part of this work), the liver was found to be “one mass of cysts, varying in size from a child’s head downwards.” The zebra’s death was purely accidental, as it broke its neck while at play in the paddock. The long bladder-worm of the horse (Cysticercus fistularia) is entirely unknown to me, and, as before suggested, may be a mere variety of the C. tenuicollis of ruminants. An authentic instance of the occurrence of the gid hydatid (Cœnurus cerebralis) in the horse is recorded by Gurlt. Lastly, in relation to the question of food, it is worthy of remark that whilst beef, veal, pork, and even mutton, are apt to be measled, the muscle-flesh of horses is not liable to be infested by Cysticerci. This is a fact in favor of hippophagy.

The nematodes of solipeds are very numerous, and first in importance must be placed the palisade worm (Strongylus armatus). This worm was known to Ruysch (1721). The old naturalists recognised two varieties (major and minor). These we now know to be merely the final stages of growth of one and the same entozoon; and in both stages the worm inflicts severe injury upon the bearer, chiefly, however, whilst wandering through the tissues. The palisade worm has acquired notoriety principally on account of its causing verminous aneurism, nevertheless, this pathological change is not, in itself, the most disastrous evil produced by the worm. In the adult state the female reaches a length of two inches, whilst the male rarely exceeds an inch and a half. The posterior ray of the caudal membrane or hood of the male is three-cleft. In both sexes the head is armed with numerous, closely-set, upright denticles, presenting the appearance of the teeth of a circular saw or trephine. The eggs are elliptical and somewhat constricted at the centre, their contents forming embryos after expulsion from both parent-worm and host. The larvæ are rhabditiform, changing their skin, in moist earth, in about three weeks, at which time they part with their long tails. According to Leuckart, they pass into the body of an intermediate bearer before entering the stomach of the definitive or equine host. From the alimentary canal they pass to the blood-vessels, causing aneurism, and thence they seek to regain the intestinal canal, where they arrive at sexual maturity. It is during their migratory efforts that they give rise to dangerous symptoms in the bearer, not unfrequently causing the death of young animals, especially yearlings. In the adult state the worm is also dangerous to the bearer, as it produces severe wounds by anchoring to the mucous membrane of the gut.

The proofs we possess as to the frequency of abdominal, especially mesenteric, aneurism from this source are overwhelming. Prof. Brüchmüller estimated the percentage of aneurismal horses, six years old and upwards, at 91 per cent., and it is a matter of common observation in veterinary dissecting rooms that verminous aneurism is rarely or never absent in the ass. Professors Dick, Simonds, Pritchard, Williams, and many other English and Scotch veterinarians of eminence, have all borne testimony of this kind, and, for myself, I may say that one of the earliest pathological appearances with which I became familiar, some thirty years back, was that presented by mesenteric arterial disease of the ass. In relation to fatal colics in the horse the study of verminous aneurism is of the highest moment. On this subject Prof. Friedberger has published some valuable lectures, in which, amongst other points, he incidentally remarks upon the comparative freedom of military horses from aneurism as compared with ordinary laboring horses. This arises partly from the fact that the latter are not cared for to the same extent, dietetically and otherwise; and, moreover, cavalry horses are, as a rule, younger than ordinary working animals. Whilst Friedberger, in his suggestive brochure, does ample justice to the writings of his colleague, Dr Bollinger, it may be said, in like manner, that he does not fail to recognise his great indebtedness to the researches of Leuckart. So practically important, however, do I deem Bollinger’s summary of the whole subject in relation to the hippopathological aspects of parasitism, that I feel it desirable to record his conclusions at full length. No professional man having any pretensions to a knowledge of the veterinary art—or, for that matter, to parasitism in relation to sanitation—should remain uninformed on this subject. Dr Bollinger’s results are thus stated:

1. The worm aneurism of the visceral arteries of the horse, existing in 90 to 94 per cent. of adult horses, has a general correspondence with the aneurisma verum mixtum of man. It is, however, distinguishable from the same by its seat, cause, character of its walls, contents, and mode of termination. The worm-aneurism arises from a parasitism of the palisade worm (Strongylus armatus), owing to an inflammatory affection of the arterial walls which it causes, and which one may describe as a recurrent traumatic endo-arteritis. This holds good for all the visceral arteries, with the exception of the abdominal aorta, in which an aneurism may arise from local increase of pressure.

2. The formation and further development of the aneurism is also favored by the narrowing of the arterial calibre, which is caused by the inflammatory swelling of its walls, and also by the contemporaneous formation of a thrombus (clot), this latter still further supporting and exciting the inflammation of the inner coat.

3. Whilst the causes above mentioned (and of these more particularly the continued presence of the palisade worms and the plugging of the smaller arteries by thrombi) favor the growth of the worm-aneurism, the small size of the same, notwithstanding the years it has existed, is explained by the considerable hypertrophy of the muscular layer, by the tough fibrous capsule formed in many cases by the connective tissue of the mesentery, and by the adhesion of the intestines to the perpendicular and free-lying anterior mesenteric artery; in particular this last-named circumstance does not allow of any very considerable shortening of the mesenteric artery, which would necessarily be accompanied by considerable dilatation of the arterial tube.

4. The favorite seat of the worm-aneurism is the trunk of the anterior mesenteric artery, directly at its origin from the abdominal aorta. Most frequently that part of the arterial trunk is dilated from which the arteria ilea, cæcales, and colica inferior (arteria ileo-cæco-colica) arise, less frequently the arteria colica superior at its origin, and the arteries of the cæcum and colon in their course in the meso-cæcum and meso-colon. The verminous aneurism also occurs in the cœliac artery (Bauchschlagader), in the posterior mesenteric artery (Gekrös-arterie), in the renal artery, and in the abdominal aorta. A horse is not unfrequently afflicted with several aneurisms of this kind at one and the same time. Thus in one case (described by Bollinger) there were six of these aneurisms affecting the abdominal aorta and its branches in the same horse. The verminous aneurism may occur from the sixth month of life onwards, and with increasing age; the number of horses free from such aneurisms becomes continually smaller.

5. The size of the aneurism varies between that of a pea and that of a man’s head. The dilatation is, as a rule, equal on all sides, the form being usually thumb-shaped or bottle-shaped, passing into that of a cone or long oval figure. This general configuration is principally due to the free and moveable situation of the anterior mesenteric artery.

6. In contrast to aneurisms in man, the walls of the worm-aneurism of the horse are almost without exception indurated. In addition to the mesenteric connective tissue, all the arterial coats, and especially the tunica media, generally take part in this induration. The hypertrophy of the media, which stands unique in respect of what is known of arterial disease, forms a compensatory action of the arterial wall, analogous to the muscular hypertrophy of the heart in valvular disease. This change in the media points to the fact that in the development of aneurism in man the early disturbance of the nutritive process in the tunica media is not a less essential factor than the degeneration of the tunica intima.

The changes in the intima are the least constant. They present all stages of progressive and retrogressive metamorphosis, from simple induration to ulceration and calcification. In the walls of the verminous aneurism one not unfrequently finds all the pathological changes exhibited by atheroma in man. Calcification is a common form of the retrograde process, and, in very rare cases, may pass on to the formation of true bone.

7. In addition to the palisade worms, one almost constantly finds a parietal thrombus contained in the aneurism. It covers the inner wall either partially or completely, being in the latter case perforated for arterial offshoots. This clot may occlude the artery, and it is not unfrequently continued into the arterial branches (peripherally) or into the aorta (centrally). Amongst the various changes that the clot undergoes, organisation of its outermost layer and softening are the most frequent. The constant occurrence of this clot is due to the presence of the worms, to the inflammation, ulcerative and regressive affection of the intima, and to the dilatation of the arterial tube.

8. The palisade worms are seldom absent from aneurisms of the horse. Their not being present is merely an accidental circumstance. On the average, nine palisade worms go to a verminous aneurism, and eleven in the horse. The highest number of worms found in one horse reached 121. Not unfrequently, also, palisade worms, or their coverings in the form of larval skins, are found in the aneurismal walls. The immigration and emigration of the palisade worms out of the intestine into the aneurism, and the reverse, take place probably, as a rule, within the arterial circulation. The path of the worm does not appear to be always the same, inasmuch as they can also wander through the peritoneal cavity. The worms found in the aneurismal walls are probably mostly only strayed specimens.

9. From a comparative pathologico-anatomical point of view, the developmental history of the aneurysma verminosum proves that a circumscribed endo-arteritis can determine the formation of an aneurism.

10. Like the worm-aneurism itself, atheroma of the abdominal arteries arises from a circumscribed acute and subacute endo-arteritis. The histological changes in the secondary atheroma of horses are perfectly analogous to those of the spontaneous atheroma of man. Idiopathic atheroma, as seen in man, does not occur any more in the horse than in the other domestic animals. Atheroma in the horse is always secondary. To be sure, one observes an idiopathic chronic endo-arteritis in many abdominal arteries of the horse, which, however, never exhibits indications of atheromatous degeneration.

11. In consequence of its position the worm-aneurism of horses is not open to physical examination, and on that account cannot be diagnosed by physical signs; moreover, it offers no characteristic symptoms. Its termination by rupture is extremely rare, the aneurisms of the abdominal aorta being more disposed to rupture than those of the anterior mesenteric artery. Of eighteen cases of known perforation, fifteen opened into the peritoneal cavity, and three into the bowel. The dangerous symptoms of the worm-aneurism are exclusively due to embolism and thrombosis of the affected artery, arising from the parietal clot. The latter becomes especially dangerous through its increasing size and the softening which often accompanies it. The absorption and shrinking of this parietal clot, be it organised or not, is materially assisted by the high pressure to which it is exposed.

12. The very marked symptoms of vascular obstruction—the sero-hæmorrhagic intestinal infarct—in embolism and thrombosis of the mesenteric arteries are easily explained by paralysis of the muscular coat of the intestine, by the absence or paucity of valves in the portal vein, by the readiness with which meteorismus (or flatus) arises, especially in herbivora, and by the loose consistence of the intestinal walls or villi.

13. The occlusion of the intestinal arteries, especially that arising suddenly, always has for its result a partial or complete paralysis of the portion of bowel which they supply. The palsy of the intestine causes the forward movement of the intestinal contents to cease, a stoppage of the fæces, a hindrance to the discharge of fæces and gas, and also that exceedingly dangerous formation of gas (within the intestinal tract) which in the herbivora is so abnormal, both quantitatively and qualitatively.

14. In embolism and thrombosis of the mesenteric arteries the symptoms during life are entirely identical with those observed in the so-called colic of horses, as has been determined by numerous observations. The partial paralysis of the bowel, which is brought on by the embolism and thrombosis of the mesenteric arteries, forms in great part the chief and leading feature of the series of symptoms known as the “colic” of horses. The palsy of the bowel which arises in this way may explain also the frequent ruptures of the digestive canal and the greater number of its changes in position. The latter are specially favored by the structure of the abdominal viscera in the horse.

15. The old changes which one finds in the peripheral branches of the anterior mesenteric artery, in the form of expired and partly absorbed embolic and thrombolic processes (pigmentation, arterial and venous thrombi), particularly in connection with those arteries which are seats of the aneurism, decisively prove that the large majority of colics resulting in recovery, so far as they do not depend upon known injuries, are caused by paralysis of the bowel from embolism and thrombosis. The sudden occurrence, course, and result of these kinds of colics also testify to their embolic origin.

16. The œdematous, inflammatory, and hæmorrhagic processes that one often finds described as the cause of death in colic, almost exclusively depend on thrombosis and embolism of the mesenteric arteries, the cases forming about 40 to 50 per cent. of all fatal colics.

17. The rapid course in fatal colics, as well as the preponderating symptoms of dyspnœa in cases of recovery, is finally due to the abnormal development of gas in the alimentary canal. In addition to the diminution of the respiratory surface by the lofty position of the diaphragm, a direct gas-poisoning (carbonic acid and sulphuretted hydrogen) probably contributes to the intensity of the symptoms and the rapid course by diffusion of the abnormally developed gas out of the intestinal canal into the blood.

18. The variety of the anatomical derangements caused by embolism and thrombosis of the intestinal arteries is faithfully mirrored by the variety of the clinical symptoms and the different degrees in the intensity and course of the colic.

19. Amongst every 100 horses afflicted with internal disease, 40 are ill with colic. Among any hundred deceased horses 40 have perished from colic, and among 100 colic patients 87 recover and 13 die. The figures prove that neither amongst the epizoötic nor sporadic diseases of horses is there any other affection which occurs so frequently, or claims anything like so many victims. Like the frequency of the worm-aneurism, the amount of disease and mortality increases with advancing age. The etiology of the colic of horses finds in the thrombosis and embolism of the mesenteric arteries, with the consequent paralysis of the bowel, an all-sufficient explanation, whilst the causes of colic hitherto accepted were for the most part insufficient.

20. In a great number of cases the thrombus of the worm-aneurism is continued past the mouth of the anterior mesenteric artery, into the lumen of the aorta, and, as such, is the exclusive cause of the embolisms of the pelvic and crural arteries which bring about the intermittent hobblings (the author says “intermitterenden Hinken,” not “Hahnentritten,” the usual equivalent term for stringhalt). Considering the excessive frequency of the thrombus being continued into the aorta, it becomes highly probable that a great part of the diseases and lameness of the posterior extremities (“Hüft und Kreuzlähme, unsichtbarer Spath, &c.,” which may be rendered “sciatic and hip or spinal lameness, obscure spavin, &c.”) are due to occlusion of the arteries.

21. Owing to the fibrous thickening of the connective tissue of the root of the anterior mesenteric round the aneurism, and to the considerable size of the latter, disturbances of the innervation of the intestine, (as well as) hindrances to the passage of the chyle, and irregularities in the portal circulation may be created, which may well lie at the root of many chronic disturbances of digestion in horses.

22. Considering the great losses and heavy social disadvantages that are occasioned by the colic of horses to the horse-breeder, to agriculture, and to the general welfare, it is of the highest importance to discover means which should prevent the introduction of the embryos with the food, and, as a consequence, the migration of the palisade worms into the mesenteric arteries of the horse.

I wish it to be distinctly understood that the above summary is translated from Bollinger (Die Kolik; s. 257). Instructive cases have been recorded both at home and abroad. Prof. Varnell has remarked that “foals and yearlings suffer more from parasites in the paddocks than they do on adjoining farms where only a few animals are bred.” This is explained by the relatively greater amount of egg-dispersion proceeding from the infected brood-mares. It is quite evident that the lives of many valuable animals are annually sacrificed by the neglect of hygienic arrangements. The palisade worm is chiefly destructive to young animals, and as Mr. Percivall has well remarked, these parasites are “commonly the cause of lingering and hidden disease, terminating in death,” without any suspicion on the part of the practitioner as to the nature of the malady. Instructive cases of this form of helminthiasis are given by Messrs Littler, Wyer, Harris, Meyrick, Litt, Percivall, Tindal, Walters, Brett, Aitken, Mead, Clancy, Baird, Mercer, Wright, Seaman, Hepburn, and others.

Fig. 63.—Larvæ of Strongylus tetracanthus. a, from the walls of the intestine (natural size); b, the same (enlarged); x, an injury; c, younger specimen (in sitû); d, the same (enlarged). Original.

Second only in clinical importance is the little four-spined strongyle (S. tetracanthus). The sexes, often seen united, are nearly of equal size, the largest females reaching nearly 3/4″. They infest the cæcum and colon, and have been found in all varieties of the horse, ass, and mule. The worm occurs in immense numbers and is a true blood-sucker. Its presence occasions severe colic and other violent symptoms, often proving fatal to the bearer. As already announced, in connection with my account of the tapeworms of the horse, this little worm may produce a virulent epidemic (epizoöty). In the sexually-immature state the worm occupies the walls of the large intestine, where it gives rise to congestion, ecchymosis, inflammation, and the formation of pus deposits. The species is readily recognised by its bright red color, by the four conical spines surrounding the mouth, by the two neck-bristles, and by the long three-lobed hood of the male, the posterior three-cleft ray having a rudimentary or fourth branch attached to its outer edge. In some specimens sent to me by Mr Whitney, I found this supplementary process fully twice as long as Schneider has represented it.

From the earliest times this entozoon has been confounded with the palisade worm. Rudolphi and several of his successors, and also in recent times Ercolani and Colin, regarded this worm as the progeny of Strongylus armatus. During my earlier examinations I likewise fell into the error of describing the immature worm as representing a new species. The parasites described by me as Trichonemes (T. arcuata) were identical with those which Prof. Dick had previously described as “worms at different stages of growth,” in his MS. sent to Dr Knox, 1836. Parasites of this kind were described by Dr Knox as “Animals similar to Trichina;” by Diesing as the “Nematoideum equi caballi;” by Mr. Littler as “Extremely small ascarides,” in a letter to Mr Varnell; by Mr Varnell himself as “Entozoa in various stages of growth;” and by Prof. Williams as “Entozoa from the intestinal walls,” in a letter to myself, dated March 13th, 1873. In reference, however, to Mr Varnell’s account of Mr Littler’s specimens I may observe that the appearances which he at first merely described as “blood spots,” he afterwards characterised as dark points “containing young worms in various stages of growth.”

As regards the course of development of this worm we have yet much to learn. Although the worm is a frequent cause of epizoöty in this country it appears to be but little known on the Continent. Krabbe makes no mention of the helminthiasis set up by the four-spined strongyle, but he points out that the young occupy the mucous membrane, in which situation they lie coiled so as to present to the naked eye the appearance of little dark spots (Husdyrenes Indvoldsorme, 1872, p. 17, ‘Aftryk. of Tidsskr. for Vet.’). However, Leuckart’s account of the appearances presented in a case brought under his notice is instructive. He writes:—“I have hitherto had only a single opportunity of examining the strongyle capsules in the intestinal membrane of the horse. Their presence is limited to the cæcum and colon, but they are so abundant in this situation that their numbers may be estimated by many hundreds. It was thus likewise in the case in question, the investigation of which by myself was rendered possible through the friendliness of Prof. Haubner of Dresden. The capsules were of oval form, and glimmered through the mucous membrane as opaque spots, mostly from one to three millimètres in size. In several of these capsules nothing was found beyond a greasy mass of a brownish color, which might readily be taken for a tuberculous substance; but the greater number of them contained a coiled worm, from three to six millimètres long, their breadth being 0·15 to 0·26 mm. (which is 1/166″ to 1/99″). They exhibited a highly colored stout intestine, and a thick-walled oral capsule of 0·022 mm. in depth and 0·025 mm. in breadth. On the dorsal side two three-cornered chitinous lamellæ arise from the shallow floor of the small oral capsule. The cuticle, notwithstanding its firm structure, was still destitute of annulations. The tail (0·15 to 0·18 mm. in length) was strongly marked off from the rest of the body, being of a slender cylindrical form with a rounded-off extremity. The development of the sexual apparatus had not yet commenced. Notwithstanding the great differences of size presented by the body, the structure of all examples was exactly the same to the minutest particular, without exception. Also the smallest specimens, which scarcely measured one millimètre, found in capsules of 0·3 mm. in diameter, were distinguishable only by the absence of the oral cup, whose position was represented by a slender and thickened chitinous cylinder, as obtains in the earliest parasitic juvenile condition of Dochmius trigonocephalus. The transformation to the form presenting an oral cup occurs through a moulting, which is accomplished already in examples of 1·5 mm. in diameter. Later, also, the worms cast their skins in their capsules, without, however, changing the oral cup. In regard to the final purpose of this metamorphosis, my investigations have left me entirely in the lurch; nevertheless, I do not entertain the smallest doubt that the worms which I have here described are the larval forms of Strongylus tetracanthus.”

Fig. 64.—Fæcal cysts or pellets containing the larvæ of Strongylus tetracanthus. Specimen (a) being enlarged (b) to show the protruding head and tail (c) of the worm. Original.

From numerous examinations I have satisfied myself that the worms after escaping the walls of the intestine—and they may often be observed in the very act of passing—re-enter the lumen of the bowel to undergo another change of skin prior to acquiring the adult state. This they accomplish by rolling themselves within the fæcal matter of the horse’s intestine. The best examples I have seen of this phenomenon occurred in a case for the clinical particulars of which I am indebted to Mr Cawthron. Most interesting was it to notice these immature worms, each coiled within a sort of cocoon, which Mr Cawthron termed a cyst. All the forty little cocoons more or less resembled pills, the bright red color of their contained worms strongly contrasting with the dark color of the cocoons. They consisted of compressed débris, which under the microscope showed many common forms of vegetable hairs and parenchyma, besides raphides and chlorophyll-granules. Internally, there was a cavity corresponding with the shape of the worm. In one instance I noticed that the worm had nearly completed its ecdysis, a portion of the old skin still remaining attached to the tail.

As already remarked, the evidence respecting the frequency and destructiveness of this little worm in England is now quite overwhelming. In a series of papers contributed to the ‘Veterinarian’ (too long for full quotation here), I have endeavoured to do justice to the “finds” and observations of those members of the veterinary profession who were good enough to supply me with valuable notes and communications. In particular must my indebtedness to Mr Rees Lloyd be acknowledged, for, as previously observed, he it was who first recognised the parasitic character of the Welsh epizoötic outbreaks. In the Deangunid and Talybont districts these strongyles proved terribly fatal to mountain ponies. It appears that the owners of the animals, as soon as they perceived anything amiss, at once disposed of them by sale, evidently anticipating fatal results sooner or later. The facts connected with some of the isolated cases brought under Mr Lloyd’s care are especially interesting, as showing the virulence of the symptoms set up. Thus on the 9th of Feb., 1875, some time after I had identified the species from specimens he had sent me, Mr Lloyd writes as follows:—“The last case I had was one which had been sold in this way, and which had suffered now and then from colicky pains for the space of about two months. The animal had been drenched with febrifuges and rubbed with stimulating liniments about the throat. However, I was sent for one evening, about an hour before the patient’s death. I soon diagnosed the case as parasitic, and at the same time considered it to be a hopeless one. I remained with it the whole of the time, of which about forty-five minutes of the most acute pain was borne by the trembling beast, which was leaping, rolling, and tossing itself about with astonishing rapidity. The bulging eyes, gnashing teeth, foaming mouth, and sharp peculiar hoarseness, were pitiable to behold; when suddenly all was silent, he quietly rose to his feet, and nipped the grass as if nought had troubled him. I then trotted him quietly up a few yards of rising ground in the corner of the field, when he immediately got down to rise no more. The next day I examined him, and found myriads of the four-spined strongyles, a large number being encysted.” Mr Rees Lloyd’s account of this case is so graphic that I have reproduced it without abridgment. Speaking of another patient, a mare, he says, “she had voided thousands of these parasites, and was in a frightfully emaciated condition, but beyond a craving appetite there was little else to be noticed.” Notwithstanding the few diagnostic indications afforded, Mr Lloyd, being led by the history of the case to suspect worms, at once examined the fæces, when he discovered thousands of these minute nematodes. Clinically, these facts ought not to be lost sight of. In addition to Mr Lloyd’s cases I have received valuable particulars of others at the hands of Prof. Williams, Messrs Cawthron, A. Clarke, T. Gerrard, D. M. Storrar, and J. W. Whitney.

Practically, it is important to inform the persons most interested that an active “drench” may be serviceable in dislodging the free intestinal worms, but the administration of purgatives must not be persevered in. As in the somewhat parallel case of Trichinosis in the human subject, the fatality of the disorder depends not upon the free and mature worms, but upon the migrating and sexually-immature forms. All attempts by means of active drugs to poison the entozoa, when once they have gained access to the tissues (whether actually capsuled or not), are worse than useless. By all means let the animals have a dose of aloes in the first instance, followed by warm bran mashes; but thereafter let every care be taken to support the patient’s strength. Especially should the exhibition of turpentine be avoided. Without doubt the cause of this, as of other similar epidemics, is primarily referable to atmospheric conditions which favor the multiplication of parasites. As the practical man cannot alter these climatal changes, he must do his best to check the disorder by removing the victims to new localities; or, if the animals must remain in infected districts, by supplying them with various kinds of artificially prepared fodder, supplemented by carefully filtered water. In this way, I believe, epidemics may be arrested, but they cannot be stamped out altogether, except by the adoption of measures which would be alike impracticable and unwarrantable.

Passing to the consideration of other intestinal nematodes, the next in importance is the large lumbricoid (Ascaris megalocephala) found in all solipeds, including the zebra. Whilst the male worms rarely exceed seven inches in length, the females sometimes reach seventeen inches. Science is indebted to Schneider for setting at rest all doubt as to the specific distinctness of this worm. The far larger number of caudal papillæ at once distinguishes it from the lumbricoid of man and the hog. The equine Ascaris may occur in any part of the alimentary canal, but the small gut forms its proper head-quarters. The entire course of development of this worm has not been traced; nevertheless, Heller found human lumbricoids measuring less than the eighth of an inch. It is not likely that any intermediate host is necessary for the growth of the larvæ, prior to their access to the definitive host. I have reared the larvæ in impure water and in moist horse-dung, up to the size of 1/30 of an inch. They were then furnished with a completely-formed digestive apparatus. Davaine kept the intra-chorional embryos alive in water for five or six years. His experiments on rats, dogs, and on a cow, led to no decisive results; but it is important to know that the eggs of lumbricoids effectually resist dryness. According to Davaine, however, embryonal development is thus arrested (except in Ascaris tetraptera of the mouse).

Seeing how readily the most ordinary attention to cleanliness must suffice to prevent lumbricoid helminthism, it is scandalous that so many severe cases of disease from this source should ever and anon turn up and be reported. In no properly conducted stable are these large entozoa ever to be seen in any considerable numbers; for so long as the water-supply is good and the fodder clean there is no possibility of infection. A fertile source of infection, however, results from allowing horses to drink at foul road-side ponds and from open waters in the vicinity of stables and paddocks where foals are reared. Into the clinical bearings of the subject I do not enter, but a host of interesting records of lumbricoid disease may be found in veterinary journals, both home and foreign. These have their counterpart in the very similar cases recorded in the medical journals, and quoted by me in the 34th bibliography of this work. From Sonsino’s report these worms do not appear very common in Egypt, but the veterinary inspector, Dr Zunhinett, had occasionally met with them. From Messrs W. Awde, J. B. Wolstenholme, and other English veterinary surgeons, I have received notes of interesting cases, but in this connection I can only further refer to the published cases of Messrs Anderson, Boddington, Cartwright, Harrison, Moir, and Wallis. The French cases, by M. Cambron and by M. Véret, are particularly instructive. Many of the cases give fatal results. In one fatal instance a pupil of mine counted over 1200 of these worms, and in a similar fatal case Mr Lewis reports that he found the small intestine literally crammed, some thousands of worms being huddled together in large masses.

Fig. 65.—Head of Oxyuris curvula. Highly magnified. After Busk.

The next nematode of general interest is the pinworm (Oxyuris curvula). Professional men often confound it with the palisade worm, and it has even been mistaken for the rat-tail maggot (Helophilus). The longest males measure 13/4″, and the females often beyond 4 inches. This worm infests the colon in great numbers, the species being easily recognised by its long subulate tail. Like its much smaller congener infesting man, this worm occasions severe local irritation, clusters of the eggs often accumulating to form yellow incrustations at the verge of the anus. Equine pinworms are vegetable feeders, and, like human Oxyurides, are conveyed to the bearer in a direct manner. No horse properly looked after can be infested by these worms. Local washings and stable cleanliness being secured by an attentive groom, the animals are safe. Prophylactic measures of this kind are all-powerful against infection. Notwithstanding the ease, however, with which the oxyuris disorder may both be prevented and cured, we find it prevails extensively everywhere, alike in mankind and in solipeds. Dr Sonsino found these parasites abundant in Egypt, some of the worms reaching a length of nearly five inches (120 mm.). Mr Emmerson has given an interesting account of the prejudicial effects of these entozoa in the horses of Singapore.

One of the most remarkable equine parasites is that which I am in the habit of calling the large-mouthed maw-worm (Spiroptera megastoma), in contra-distinction to the small-mouthed species (S. microstoma). In this country the worm has attracted little notice, but through the kindness of Mr Spooner Hart, of Calcutta, and of Mr Percivall, of the 11th Hussars, stationed at Umballa, I have had abundant opportunities of examining this entozoon and the singular pathological appearances which it occasions. This parasite was first described by Rudolphi, who says:—“Spiroptera capitis discreti ore magno nudo, cauda feminæ rectiuscula acuta, mavis simpliciter spirali, corpusculis rotundis ad basim penis styliformis.” The worm was afterwards observed by Schultze, Chabert, and frequently also by Andral, but the best accounts of it are those given by Gurlt, Valenciennes, and Dujardin. Schneider has likewise done much to set at rest disputed points. Respecting the Spiroptère du Cheval, Dujardin, writing in 1844, observes that “Rudolphi at first studied this helminth from examples found in great number by Reckleben, at Berlin, in tubercles of the stomach of two horses. Quite recently, M. Valenciennes, at Paris, has found it frequently in tumours, from twenty to forty millimètres in size, in the stomach of eleven horses out of twenty-five that he had subjected to this kind of research. These tumours, lodged between the mucous and muscular layers of the digestive canal, are perforated by several holes traversing the mucous membrane. They are divided internally by a number of folds into numerous intercommunicating cavities, and sometimes filled with solid mucus and very many spiropteras. It is from examples collected by M. Valenciennes that I have been able to study the parasite.”

As regards the description of the worm, it is almost needless to say that Dujardin’s account is minute and admirable in all respects. In fact, no naturalist ever exceeded the Rennes savant in carefulness and accuracy of detail. An interesting point connected with these stomach-worms lies in the circumstance that Gurlt recognised two varieties, one of which he termed Sp. meg., var. major. It remained for Schneider to show that the larger worms formed an altogether distinct species, which he termed Filaria microstoma (‘Monogr.,’ l. c., 1866, s. 98). It was not unnatural that Rudolphi and his successors should confound these two forms together, and it is also not a little curious that the smaller of the two species has the larger mouth. Practically, veterinarians will probably rest content to know that whilst the Spiroptera megastoma occupies tumours in the walls of the stomach, the S. microstoma is always to be found free in the cavity of that organ. Any helminthologist who may chance to have read the Ceylon Company’s report on the fatal epidemic affecting the mules of the Mauritius in 1876 can scarcely fail to have observed that the worm called Ascaris vermicularis by Mr Bradshaw is none other than our Sp. megastoma. The description of the tumours as “reticulated” sufficiently explains their honeycomb-like appearance, but I think that the expression “alveolar” would better convey their true pathological character. Mr Spooner Hart compared these structures, which he terms “abodes,” to mole-hills, but there is no good ground for supposing that the wanderings of the parasites are in any sense comparable to the burrowings of the mole. In like manner the expression “nidus,” employed by Mr Bradshaw, though suggestive of their nest-like appearance, is to some extent misleading, as it implies that the worms form a nide or brood. Possibly, it may turn out that all the nematodes in each tumour have been bred in the spot where they are found, but hitherto they have only been seen in the adult state. Earlier stages of growth should be diligently sought for. Widely dissimilar as the two maw-worms are, it would not greatly surprise me to learn that Sp. megastoma and S. microstoma are dimorphic conditions of one and the same entozoon. At all events, Ercolani’s determination of the relations subsisting between Ascaris inflexa and A. vesicularis suggests a possible analogy of this kind. I may mention that the male Spiroptera megastoma reaches nearly one third and the female one half of an inch in length. A constriction separates the head from the body. The mouth is surrounded by four thick horny lips, the dorso-ventral pair being the larger. The tail of the male is spirally twisted, and furnished with lateral bands supported by three or four ribs. It carries two curved spicules of unequal size. There are five pairs of caudal papillæ, the tail being bluntly pointed in both sexes. The vulva of the female is placed about 1/7″ below the head. The eggs are linear or very narrow, and furnished with thick shells. According to Sonsino, who found Sp. megastoma in five out of sixteen Egyptian horses, the verminiferous growths are usually seated near the pyloric end of the stomach, as many as four tumours occurring at one time. Neither Sonsino nor any other observers already quoted appear to think that these morbid changes in any way interfere with the healthy performance of the gastric functions. However, I am of opinion that at least one recorded fatal case of parasitism, producing rupture of the stomach, affords an instance, however rare, of the injurious action of this entozoon. It is reported under the signature of “Argus,” quoted below.

In this connection I may mention that in 1864 Prof. Axe observed some small worms, scarcely visible to the naked eye, in the mucous membrane of the stomach of a donkey, the same worms being subsequently observed in three other donkeys brought to the dissecting room of the Royal Veterinary College. From the examination of a drawing of one of the male worms, executed by Prof. Simonds, I am led to believe that the parasites are entirely new to science. The hood being well marked there can be no doubt as to the strongyloid affinities of the worm. I therefore propose to call the worm after its discoverer (Strongylus Axei).

In regard to Sp. microstoma, the males measure up to 2/3″, whilst the females have a long diameter of 3/4″ or rather more (10‴). The small-mouthed maw-worm lives free in the stomach, and, as Krabbe observes, not unfrequently in very considerable numbers. It does not appear to be capable of injuring the host.

One of the most interesting equine nematodes is the eye-worm. Most veterinary writers speak of it as the Filaria oculi, but to helminthologists it is better known by the more correct designation, F. papillosa. Though commonly obtained from the eyeball and its tunics, the worm infests various tissues and organs of the body, being found in the thorax, abdomen, membranes of the brain, muscles, and cellular tissues. It infests the ass and mule, and also horned ruminants. The males attain a length of three inches and the females seven inches. The head is broad, with a gaping mouth armed with a ring of chitine and two prominent denticles. There are also two papillæ on the neck near the middle line, besides sixteen caudal papillæ, eight on either side. The tail of the male is spirally twisted, that of the female only slightly curved. Notwithstanding the many opportunities afforded of examining this parasite in the fresh state, very little is known respecting its origin and course of development. Dr Manson, who found that the mouth was armed with a five- or six-toothed oral saw, considers that the eye is not a proper resting place for the parasite, and that when one wandering worm comes across the track of another it follows it up from sexual instinct, and thus several may be found together in one place. The tracks are readily seen by the naked eye. Dr Sonsino speaks of it as a “yellow line.” This Italian observer found the worm in twelve out of the sixteen solipeds he examined during the plague. Each horse showed from two to a dozen worms “in the peritoneal cavity, wandering free on the serous lining, without causing any apparent mischief to the membrane.” On one occasion Sonsino found the worm in the liver. From the similarity of habit there can be little doubt that the cases of guinea-worm (F. medinensis) recorded by Clarkson and others, as occurring in the horse, were merely examples of F. papillosa. I think so all the more because the lamented Fedschenko verbally expressed to me his astonishment that I had in my introductory treatise (p. 387) spoken of the Dracunculus as an equine parasite. I did so on the authority of others. To the Rev. Horace Waller I am indebted for specimens of the eye-worm brought from Assam, and to Mr Spooner Hart for others sent from India. For examples occurring in England I am indebted to Mr Haydon Leggett, who, in 1875, sent me three specimens extracted from the eye of a five-year-old mare. Mr Steel has also given me an example of F. papillosa taken from the peritoneum of a donkey. Similar cases are constantly occurring in the practice of veterinarians in Hindostan. Highly interesting Indian cases are recorded by Kennedy, Molyneux, Twining, and Breton, and in addition to these I may also particularise those of Macnamara, C. Percivall, Hickman, Clarkson, Skeavington, and Jeaffreson. The cases by Lee and Grellier also deserve attention.

Another species of thread-worm (Filaria lacrymalis) is occasionally found in the horse between the lids and eyeball. It is a comparatively small and harmless parasite, the males measuring 1/2″ in length and the females 2/3″. It also infests the ox. Both the large and small eye-worms are viviparous, and, not improbably, both of them are the means of conveying embryonic Filariæ into the circulation. Be this as it may, we owe to Dr Sonsino the discovery of hæmatozoa in an Egyptian horse. The larval worm was provisionally named by him Filaria sanguinis equi. The microscopic nematodes closely resemble the larvæ of F. sanguinis hominis, but they are smaller. The horse from whose blood Dr Sonsino obtained the minute worms was also found, by post-mortem examination, to have been infested by Filaria papillosa, a circumstance which naturally suggested a genetic relation between the larval and adult parasites. Similar, if not the same, microscopic worms had been previously discovered by Wedl, who primarily and independently regarded them as embryos of F. papillosa. Another curious filaria-like entozoon is the reticulated threadworm (Onchocerca reticulata). In England we have no acquaintance with this singular parasite, but it appears to be tolerably common in Italy. Excellent figures of it have been given by Diesing. Both males and females are in the habit of coiling themselves within the muscles, where they are found invested by a capsule of connective tissue. When unrolled the sexes are found of equal size, acquiring a length of 11/2″. The worm has a simple unarmed mouth, its body being marked by a series of annulations formed of incompletely anastomosing rings. It does not appear to possess any clinical importance.

In connection with the equine nematodes I need only mention the lung-worm (Strongylus micrurus). Its importance in relation to the production of husk or parasitic bronchitis in calves has already been considered. The worm is rarely productive of mischief amongst solipeds, nevertheless, in the dissecting-room subjects at the Royal Veterinary College, the presence of these parasites in the lungs is frequently noticed. Lastly, it only remains for me to observe that the renal strongyle (S. gigas) is occasionally seen in the horse. In 1792 M. Chabert found one in the left kidney, and similar cases have since either been witnessed or reported by Rudolphi and Leblanc.

Of the numerous insect parasites and tormentors of solipeds the gadflies (Œstridæ) demand chief attention. For special description of the forms, Brauer’s monograph is the most, and, in fact, the only reliable authority. Here it is not possible to give the characters of the various equine species, of which at least half a dozen are known to science. As remarked by me in the special chapter contributed to Prof. Williams’ well-known veterinary treatise, the common gad-fly (Gastrophilus equi) attacks the animal whilst grazing late in the summer, its object being, not to derive sustenance, but to deposit its eggs. This it accomplishes by means of a glutinous excretion, causing the ova to adhere to the hairs. The parts selected are chiefly those of the shoulder, base of the neck, and inner part of the fore legs, especially about the knees, for in these situations the horse will have no difficulty in reaching the ova with its tongue. When the animal licks those parts of the coat where the eggs have been placed, the moisture of the tongue, aided by warmth, hatches the ova, and in something less than three weeks from the time of the deposition of the eggs, the larvæ make their escape. As maggots they are next transferred to the mouth, and ultimately to the stomach along with food and drink. A great many larvæ perish during this passive mode of immigration, some being dropped from the mouth, and others being crushed in the fodder during mastication. It has been calculated that out of the many hundreds of eggs deposited on a single horse, scarcely one out of fifty of the larvæ arrive within the stomach. Notwithstanding this waste the interior of the stomach may become completely covered with “bots.” Whether there be few or many, they are anchored in this situation chiefly by means of two large cephalic hooks. After the bots have attained perfect growth they voluntarily loosen their hold, and allow themselves to be carried along the alimentary canal until they escape with the fæces. Many persons suppose that during their passage through the intestinal canal they re-attach themselves to the mucous membrane, thereby occasioning severe intestinal irritation. This is an error. In all cases they sooner or later fall to the ground, and when transferred to the soil they bury themselves beneath the surface, in order to undergo transformation into the pupa condition. Having remained in the earth for a period of six or seven weeks they finally emerge from their pupal-cocoons as perfect dipterous insects. It thus appears that bots ordinarily pass about eight months of their lifetime in the digestive organs of the horse.

That they are capable of giving rise to severe disease there can be no doubt, but it is not often that the disorder is correctly diagnosed, since it is only by the passage of the larvæ that the practitioner can be made aware of their presence. Mr J. S. Wood has published a case of tetanus in a mare, associated with the larvæ of Œstrus equi, and Mr J. T. Brewer has also given a case where the duodenum was perforated by bots. Mr Goodworth records an instance of pyloric obstruction from the same cause, and Mr W. Coupe informed me in 1876 that he had a drove of foreign ponies under his care, all of which suffered irritation from hæmorrhoidal bots. He removed them with a pair of forceps. Although frequently said to do so, the common bot does not attach itself to the rectum before finally escaping the host. The larvæ of G. hæmorrhoidalis normally reside there. In this situation they seriously inconvenience the bearer. The bots of G. nasalis are often confounded with those which ordinarily occupy the stomach of the bearer. The larvæ of G. nasalis commonly reside in the duodenum near the pylorus. According to Schwab and Brauer, they rarely occupy the stomach. As occurs in the common species, this bot passes away with the fæces, and does not attach itself to the lower bowel. The bots of Brauer’s G. inermis much resemble those of G. equi, but they are much smaller and attach themselves to the wall of the small intestine. The bots of G. pecorum, which dwell in the rectum, are readily recognised by their peculiar form and scanty spination. They are pointed in front and truncated posteriorly. An assinine variety of G. equi has been described by Bilharz, whilst another distinct species (G. flavipes) attacks the ass and mule. The bot-larvæ of the latter host require recognition and description. A great variety of other equine bot-flies have been described, but all, or nearly all, of them are mere synonyms of the above-mentioned forms. For the limitation of the species I accept Brauer’s authority, and likewise his nomenclature. A great deal of nonsense has been written respecting bots. It is a relief to believe that G. (Œstrus) veterinus, G. ferruginatus, G. jubarum, G. (Œ.) Clarkii, G. salutiferus, G. subjacens, and many others, are not good species, at least that they are mere synonyms. In regard to the occurrence of subcutaneous bot-like maggots in the horse and ass, no doubt need exist on this point. I am indebted to Mr Percy Gregory for characteristic specimens taken from the back, neck, and withers of a four-year-old gelding. They appear to correspond with the Hypoderma Loiseti of Joly. Similar maggots have been found in the ass by Herr Erber, but Brauer refers these to H. silenus. Prof. Brückmüller published a case where the brain was infested by larvæ; and Mr Shipley has sent me an example of H. equi, which he states he removed from the choroid plexus of the brain. In addition to the cases by Woods, Goodworth, and Brewer, already quoted, others have been published by Tyndal and Cartwright.

Amongst the numerous other parasitic dipterous larvæ one must notice the rat-tailed maggots (Helophilus). A genuine instance of this kind has been brought under my observation, but the example recorded by Professor Axe was spurious. Professor Simonds and myself saw this supposed maggot, which was merely a very stout and pregnant Oxyuris curvula. Another genuine case was published by Mr. Stanley. This is quoted by A. Numan in his essay on Cœnurus. I have previously mentioned my having received an Helophilus-larva that had passed from the human body. One of the most troublesome external parasites is the so-called horse-tick or forest-fly (Hippobosca equina). They attack the abdomen, flanks, and inner part of the thighs in great numbers, occasioning great distress to the bearer. Being of leathery toughness their bodies are not easily crushed, and they are removed only with great difficulty. There is an equine disease in Sweden called Stackra, which is erroneously attributed to injuries produced by a species of fly-maggot (Lixus) which lives on the fine-leaved water-drop wort (Phellandrium). As regards the so-called free parasites, or rather non-parasitic obnoxious insects, which torment solipeds, it is impossible even to enumerate them. The tsetse of South Africa (Glossina morsitans) is terribly fatal to the horse, but it is said that the mule, ass, and zebra do not suffer from its bites—an immunity shared by swine, goats, antelopes, and man himself. Major Vardon’s rash experiment (based on the supposition that horses deprived of fresh green food would not suffer from the attacks of the fly) proved fatal to an animal which he purposely exposed on a much infested hill-top. The horse died ten days after it was bitten. According to Chapman, the bites of four tsetse flies are sufficient to kill an ox, but in man the irritation produced is very slight. Amongst other insects proving troublesome to solipeds may be mentioned the leg-sticker (Stomoxys calcitrans), the clegg (Hæmatopota pluvialis) which is very abundant in the West Highlands, various species of Tabanidæ and Asilidæ (Tabanus autumnalis, T. bovinus, Chrysops cæcutiens, Asilus crabroniformis), and also a host of ordinary flies and gnats (Muscidæ and Tipulidæ), as, for example, Anthomyia meteorica and Culex equinus. In India the bite of a species of Simulia gives rise to the formation of open sores of the most intractable character. As regards hemipterous insects it may be said that many species of lice (Anoplura) produce what is called phthiriasis or lousiness in the horse, some of them being derived from poultry. The best known species are Trichodectes equi, T. scalaris, Hæmatopinus equi, H. vituli, H. eurysternus, and the ass-louse (H. asini). Of the half dozen or more species infesting the hen (belonging to the genera Goniocotes, Liotheum, &c.) it is not probable that more than one or, at most, two of them are concerned in the production of poultry-lousiness in the horse. As an equine disorder this kind of phthiriasis was first described by Bouley. Cases in England have been observed by Messrs. Henderson, Moore, and Woodger. For some account of cases of lousiness due to Hæmatopinus I am indebted to Mr S. Butters. As regards the scab, itch, and mange insects or mites (Acaridæ), three perfectly distinct forms are known. Adopting M. Mégnin’s classification they are Sarcoptes scabiei, var. equi, Psoroptes longirostris, var. equi (being the Dermatodectes equi of Gerlach), and Chorioptes spathiferus, var. equi, which is the Symbiotes equi of Gerlach. All the species have been beautifully illustrated by M. Mégnin, whose memoir has dispersed many of the clouds of error and misrepresentation which have hitherto surrounded the subject. Whilst Psoroptes forms the true horse-mite, and attacks various parts of the body, Chorioptes confines its attacks to the posterior regions. Messrs South and Day and myself have verified some of the facts recorded by Mégnin in respect of the structure and habits of this last species. Another kind of mite (Glyciphagus hippopodos) is stated to infest the ulcerated feet of horses. It would appear that no true ticks properly belong to solipeds; nevertheless, the common cattle-tick (Ixodes bovis) occasionally attacks horses. Probably several other species of Ixodidæ, known to infest other animals, behave in the same way. The Arachnidan called Pentastoma tænioides, though properly belonging to the dog, has on several occasions been detected in the nasal or frontal sinuses of the horse. Such instances are recorded by Chabert and Greve. The largest example of this singular entozoon seen by myself was obtained from the same situation, and presented to me by the late Mr C. B. Rose, whose writings I have frequently quoted in connection with the Cœnuri of rabbits.

Bibliography (No. 50).—Aitken, J., “Worms in the Spermatic Artery of a Colt,” ‘Veterinarian,’ p. 683, 1855.—Anderson, J., “A Case of Strangulation of the Ileum (with Lumbrici),” ‘Veterinarian,’ p. 261, 1859.—(Anonymous), “Rupture of the Stomach, associated with the existence of Cysts between its Coats containing Worms,” ‘Veterinarian,’ March, 1864, p. 151.—(Anon.), “Extraction of Filaria oculi from the Horse,” by “Miles,” ‘Veterinarian,’ 1864, p. 218.—(Anon.), “Case of F. oculi in the Horse,” ‘Veterinarian,’ 1864, p. 218.—(Anon.), “Worms in the Coats of the Stomach of a Horse,” by “Argus,” in the ‘Veterinarian,’ 1865, p. 151.—Baird, W., “Notice of Sclerostoma in the Testicle of the Horse,” ‘Proc. Zool. Soc.,’ 1861.—Blanchard, “Anoplocephala perfoliata,” ‘Ann. des Sci. Nat.,’ 3rd ser., tom. x, p. 345.—Bollinger, O., ‘Die Kolik der Pferde und das Wurmaneurisma der Eingeweidearterien,’ Munchen, 1870. (Reviewed by myself in the ‘Veterinarian,’ Jan.–April, 1874.)—Bovett, “Existence of Filariæ in a Sinuous Ulcer of the Withers of a Mare,” ‘Veterinarian,’ p. 515, 1861.—Bradshaw, C., “Death of Mules from Parasitic Disease in the Mauritius (with remarks by Dr Cobbold),” ‘Veterinarian,’ Dec., 1876, p. 837.—Brauer, F., ‘Monographie der Œstriden,’ Wien, 1863.—Idem, “Œstr. (Hypoderma) Clarkii,” in ‘Verhandl. der zool.-bot. Gessellsch. in Wien,’ xxv, p. 75.—Idem, “On Cephenomyia trompe from the Reindeer,” ibid., p. 77.—Idem, “Hypoderma bonassi from the American Buffalo,” ibid. (all with figs.), 1875.—Breton, “On the Worm found in the Eye of the Horse,” ‘Calcutta Med. and Phys. Soc. Trans.,’ vol. i, 1825, p. 337.—Brown, D. S., “The Œstrus equi, or Horse-bot,” the ‘Veterinary Journal,’ July, 1877, p. 14.—Brückmüller, “Larvæ in the Brain of a Foal,” from ‘Viert. für wissensch. Vet.,’ in ‘Veterinarian,’ p. 82, 1857.—Cartwright, W. A., “On Strangulation of the Bowels, associated with about 150 Bots, and also some 150 Ascarides, in the Horse,” ‘Veterinarian,’ p. 413, 1833.—Idem, “Case of about 200 ‘Bots in the Œsophagus’ of a Horse,” ibid., p. 400, 1828.—Chambron, “On a Parasitic Malady in the Horse,” from ‘Ann. de Méd. Vét.,’ in ‘Edin. Vet. Rev.,’ 1861; see also (Cambron) ‘Veterinarian,’ 1860, p. 612.—Clark, B., “Obs. on the genus Œstrus,” ‘Linn. Trans.,’ vol. iii, p. 289, 1797.—Idem, ‘An Essay on the Bots of Horses and other Animals,’ London, 1815.—Clarkson, N. F., “Case of Filaria oculi in the Horse,” ‘Vet. Rec.,’ vol. i, p. 73, 1845.—Idem, “Case of Filaria medinensis in the Horse,” ibid., 1845.—Cobbold, “On the Diptera (bots),” in a chap. on the Parasitic Diseases of Animals, in Williams’ work (l. c., Bibl. No. [48]).—Idem, “Obs. on rare Parasites from the Horse,” ‘Veterinarian,’ Feb., 1874.—Idem, “Further remarks on rare Parasites from the Horse,” ibid., April, 1874.—Idem, “Fatal Epid. affecting Ponies,” ibid., June, 1874.—Idem, “Remarks on Mégnin’s Tapeworm,” ibid., Sept., 1874.—Idem, “Report on Parasites (sent from India by F. F. Collins and Spooner Hart),” ibid., Nov., 1874.—Idem, “Epizoöty in the Horse, more especially in relation to the Ravages produced by the Four-spined Strongyle (S. tetracanthus),” ibid., April, 1875.—Idem, “The Egyptian Horse Plague in relation to the question of Parasitism,” ibid., Nov., 1876.—Idem, “Description of the new Equine Fluke (Gastrodiscus Sonsinoii),” ibid., April, 1877.—Idem, “On Worm-like Organisms within the Mitral Valve of a Horse,” ibid., 1877.—Idem, “Entozoa of the Horse and Elephant” (see Bibl. No. [51]).—Idem, “Observations respecting the Large-mouthed Maw-worm of the Horse,” ‘Veterinarian,’ Jan., 1877.—Couchman, T., “Worms in the Kidney of a Colt,” ‘Veterinarian,’ p. 145, 1857.—Coupe, W., “Fatal Parasitism in a Colt,” ‘Veterinarian,’ Dec., 1876, p. 844.—Davaine, “Les Cestoides,” in ‘Dict. Encycl. des Sci. Méd.,’ p. 591.—Dick (see Knox).—Dickens, C., “Joint-lameness in Colts, associated with and symptomatic of Lumbricoid Worms,” ‘Veterinarian,’ p. 601, 1863.—Dun, R., “Remarks on Entozoa of the Horse,” ‘Veterinarian,’ 1854, p. 445.—Dupuy (with M. Prince), “Filariæ in the Great Mesenteric of a Horse,” ‘Veterinarian,’ 1835, p. 570.—Emmerson, C., “Prevalence of Entozoa among Horses in the Island of Singapore,” ‘Veterinarian,’ 1861, p. 514.—Friedberger, F., ‘Die Kolik der Pferde,’ Berlin, 1874. (Reviewed by me in the ‘Veterinarian,’ Jan.–April, 1874.)—Fry, “Case of Worms in the Horse,” ‘The Hippiatrist,’ &c., vol. iii, p. 10, 1830.—Gamgee, J. (senior), “On Bots,” ‘Edin. Vet. Rev.,’ July, 1858.—Goodworth, S., “Obstruction of the Pyloric Orifice of the Stomach by Bots,” ‘Veterinarian,’ p. 410, 1837.—Grellier, J., “On the Worm in the Eye (of the Horse),” ‘Veterinarian,’ p. 18, 1844.—Harlan, R., “Case of a Colt killed by Worms,” in his ‘Med. and Phys. Researches,’ p. 554; see also ‘Med.-Chir. Rev.,’ 1836.—Harris, “A Case of Worms in the Arteries of a Colt,” ‘Veterinarian,’ p. 307, 1834.—Harrison, J. D., “The singular effect of Worms in the Stomach of a Mare,” ‘Veterinarian,’ p. 331, 1842.—Hickman, T., “Worm in the Eye of the Horse,” ‘Edin. Vet. Rev.,’ 1864, p. 653.—Hopkinson, F., “Account of a Worm in the Horse’s Eye,” from ‘Trans. of Amer. Phil. Soc.,’ in ‘Med. Comment.,’ vol. xi, p. 166, 1784.—Hutchinson, J., “Hydatid in the Eye of a Horse,” ‘Path. Soc. Trans.,’ and rep. in ‘Lancet,’ 1857.—Huxley, “On Echinococcus (from the Zebra),” see Bibl. No. [20, o].—Jeaffreson, W., “Case of Removal of a Worm from the Eye of an Arab Horse,” ‘Lancet,’ p. 690, 1836–37, and ‘Veterinarian,’ p. 471, 1837.—Kennedy, M., “Account of a Nondescript Worm (Ascaris pellucidus) found in the Eyes of Horses in India,” ‘Trans. Roy. Soc. Edin.,’ vol. xi, p. 107, 1816.—Kirkman, ‘Hydatids’ (see Bibl. No. [20, o]).—Knox, ‘Edin. Med. and Surg. Journ.,’ 1836.—Krabbe (l. c., in text).—Lee, C. A., “On Filaria papillosa in the Anterior Chamber of the Eye of a Horse (and on Filariæ in general, &c.),” ‘Amer. Journ. Sci. and Art.,’ vol. xxxix, p. 278, 1840.—Lessona, G., “On the Bot (or Œstrus) of the Horse,” from ‘Recueil de Méd. Vét.,’ in ‘Veterinarian,’ p. 156, 1854.—Leuckart (l. c., in text).—Litt, W., “A Singular Case (of an immense number of Worms in a Colt),” ‘Veterinarian,’ p. 529, 1852.—Macnamara, “On F. papillosa in the Eye of Man and the Horse,” ‘Indian Ann. Med. Sci.,’ 1864.—Marcet (see Bibl. No. [34]).—Mead, J., “A Worm in the Scrotum of a Colt,” ‘Veterinarian,’ 1843, p. 648.—Mégnin, “Petit Tænia inorme du Cheval,” in ‘Bull. de la Soc. Cent. de Méd. Vét.,’ t. vi, 3e série, p. 112.—Idem, ‘Monog. de la tribu des Sarcoptides,’ &c.; see also review by myself in the ‘Veterinarian,’ Aug., 1877.—Mercer, J., “On Entozoal or Worm-aneurism,” ‘Lond. Med. Gaz.,’ 1847, and in part x of “Contrib. to Zool. Path.,” in the ‘Veterinarian,’ p. 33, 1846.—Meyrick, J., “Death of a Colt from Entozoa within the Abdomen,” ‘Veterinarian,’ 1859, p. 695.—Moir, J., “Rupture of the Ileum resulting from Worms,” ‘Veterinarian,’ 1857, p. 265.—Molyneux, R., “On Worm in the Eye of Horses in India,” ‘Veterinarian,’ 1828, p. 309.—Morgan, A., “Case of Hydatid in the Brain of a Mare,” ‘Veterinarian,’ p. 396, 1855.—Numan, A., ‘Ueber die Bremsen Larven, im Magen der Pferde,’ 1837.—Idem, “Entozoon (Monostoma settenii) from the Eye of a Horse,” from ‘Tidschr. voor naturl. Geschied. en Physiol.,’ 1842, in ‘Med.-Chir. Rev.,’ 1842.—Idem (for remarks on Cysticercus fistularis), ‘Over den veelkop blaasworm’ (l. c., Bibl. No. [49]), p. 263.—Peall, T., “A Discourse on ‘Worms,’” at p. 37, in his ‘Observations, chiefly practical, on some of the more common Diseases of the Horse,’ pub. at Cork, 1814.—Percivall, C., “Worm in the Eye of the Horse (two cases),” ‘Veterinarian,’ p. 75, 1828.—Percivall, J., “A Case of Ascarides in the large Intestines of the Horse,” ‘Veterinarian,’ p. 358, 1829.—Poulton, T. J., “Large numbers of Parasites in the Intestines of a Mare,” ‘Veterinarian,’ 1866, p. 385.—Seaman, J., “Worms in the Blood-vessels of Horses and Colts,” ‘Edin. Vet. Rev.,’ 1864, p. 520.—Simonds, “On Disease of the Mesenteric Artery, produced by Strongyli,” ‘Path. Soc. Trans.,’ 1854.—Skeavington, G., “On Worm in the Eye of the Horse (three cases),” ‘Veterinarian,’ 1834, p. 196.—Sonsino, P., “On the Entozoa of the Horse in relation to the late Egyptian Equine Plague,” ‘Veterinarian,’ Feb. and March, 1877.—Tyndal, J., “Worms in the Intestines of a Mare,” ‘Veterinarian,’ 1843, p. 629.—Twining, W., “Obs. on the Filaria or Threadworm found in the Eyes of Horses in India,” ‘Calcutta Med. and Phys. Soc. Trans.,’ vol. i, p. 345, 1825; rep. in ‘Veterinarian,’ p. 114, 1828.—Valenciennes, “On the Spiroptera megastoma of Gurlt,” abstract of a paper from Acad. Sci. of Paris, reported in ‘Lancet,’ 1843.—Varnell, “Remarks on Cases of Parasitic Disease in Horses,” ‘Veterinarian,’ p. 201, 1864.—Veret, “Perforation of the small Intestines by Ascarides lumbricoides (in the Horse),” from ‘Rec. de Méd. Vét.,’ in ‘Veterinarian,’ p. 569, 1837.—Vincent, “Curious case of Incurable Lameness from Hydatids,” ‘Veterinarian,’ 1848, p. 674; see also p. 3, ibid.—Wallis, “Note on the occurrence of (250) Lumbrici in a Horse,” ‘Veterinary Record,’ 1849, p. 300.—Walters, R. G., “Parasites in the Kidneys of a Mare,” ‘Veterinarian,’ 1866, p. 265.—Woodger, “Hydatid in the Brain of a Horse,” ‘Veterinarian,’ 1863, p. 75.—Woods, J. S., “Tetanus in a Mare, associated with the Larvæ of Œstrus equi within the Stomach and Duodenum,” ‘Veterinarian,’ 1859, p. 693.—Wright, “Strongyli in the Scrotum of a Colt,” ‘Veterinary Record,’ 1849, p. 385.—Youatt, “Worms between the Tunics of the Stomach,” ‘Veterinarian,’ 1835, p. 571.—Idem, “Tetanus, Worms in the Trachea, and Dilatation of the Heart, in a Zebra,” ibid., p. 504, 1836.—Idem, “Worms in the Nasal Cavity of the Horse,” ibid., p. 329, 1832.—Zangger, “Remarks on Entozoa,” from the French, ‘Veterinarian,’ 1855, p. 463.

Part X (Pachydermata)

Concerning the parasites and parasitic diseases of this miscellaneous assemblage of large mammals, I shall first speak of those of the proboscideans (Elephantidæ). Except by myself, they have been but little studied, and I am yet waiting for an opportunity to give further time to their consideration. When Diesing published his ‘Systema’ only two helminths were referred to the Indian elephant, namely, Ascaris lonchoptera and an undescribed fluke supposed to be a distome. The whole subject requires revision, but I think the following species must, for the present at least, be allowed recognition:—Fasciola Jacksoni (mihi), Amphistoma Hawkesii (mihi), Ascaris lonchoptera (Diesing), Sclerostoma Spinuliferum (Baird), and Dochmius Sangeri (mihi). Either the Ascaris or the Sclerostoma is probably identical with Rudolphi’s Strongylus elephantis.

At the Norwich Meeting of the British Association, in 1868, I exhibited two flukes received from J. S. Thacker, V.S., of the Madras Army. They were handed to me by the late Dr Baird, and were labelled “Distoma taken from liver of elephant and forwarded for classification.” I stated at the time that these entozoa were identical with certain flukes previously obtained from the duodenum and biliary ducts of an Indian elephant, and which, though carefully preserved in the Boston Museum, U.S., had never been properly described. They were only briefly noticed by Dr Jackson in his ‘Descriptive Catalogue’ of the Museum. In the summer of 1868 fifteen specimens of fluke, removed from Burmese elephants, had been forwarded to and received by Professor Huxley from Rangoon, accompanied by a statement to the effect that they were the cause of an extensive and fatal disease in Burmah. Through the kindness of Prof. Huxley I was allowed to make use of his specimens for the purpose of comparison and identification, and thus it became evident that our specimens were of the same species. It was also evident that the species could be none other than that represented by the Boston specimens. Further examination having made it clear that the organisation of these flukes departed from the ordinary distome type, I named the parasite Fasciola Jacksoni, at the same time offering the following description (‘Entozoa,’ Supp., 1869, p. 80):—“Body armed throughout with minute spines, orbicular, usually folded at either end towards the ventral aspect, thus presenting a concavo-convex form; oral sucker terminal, with reproductive papillæ about midway between it and the ventral acetabulum; intromittent organ 1/4″ in length; digestive apparatus with two main zigzag-shaped canals, giving off alternating branches at the angles thus formed, the ultimate cæcal ramifications occupying the whole extent of the body; length, when unrolled, from 1/2″ to 5/8″, breadth 1/3″ to 1/2″.” Now, if reference be made to the appendix of the late C. M. Diesing’s ‘Systema Helminthum,’ it will be found that Jackson’s statement had not escaped that helminthologist’s notice, though, not having seen any specimens, he was not unnaturally led to place the species amongst the distomes proper. In Diesing’s subsequently published ‘Revision der Myzelminthen,’ the species is formally characterised as the Distomum elephantis of Jackson (‘Sitzungsberichte d. Math.-nat. Cl. d. k. Akad. d. Wissenchaften,’ Bd. xxxii, 1858). In my “Synopsis of the Distomidæ,” which appeared in the ‘Journal of the Linnean Society’ for 1861, I had also placed it amongst the distomes, not considering it to be a doubtful form (‘Proceed. Linn. Soc.,’ “Zoology,” vol. v, p. 9). These references exhausted the literature of the subject up to the time of the issue of my ‘Manual’ in 1873, where this fluke is again briefly noticed (p. 13). Several of Prof. Huxley’s specimens have been added to the entozoological department of the Hunterian Museum. It is clear that all these notices and descriptions point to the same parasite. The worm has since been more carefully described by Dr R. H. Fitz, from a series of dissections and preparations made by Dr H. P. Quincy, and deposited in the Warren Museum, Boston, U.S.

About the middle of June, 1875, I received a letter from General Hawkes, of the Madras Staff Corps, dated Secunderabad, May 12th, 1875, and in reference to the subject before us he writes as follows:—“My attention has been recently directed to a very unusual mortality of elephants at this station. Out of twenty-eight elephants under my charge, no less than twelve have died within the last sixteen months, whereas the average annual mortality has been hitherto only two per annum out of thirty-eight in our establishment. In every case of death there appeared to exist serious organic disease quite sufficient to account for such death, but as the mortality increased I had a post-mortem examination made in each case; and although here also organic disease sufficient to account for death was present in each case, yet in every one of these elephants we found the liver-fluke in greater or less abundance.” General Hawkes adds:—“Meanwhile I have sent you a small box containing three bottles, one containing the liver-fluke (Fasciola Jacksoni) referred to in your work on the parasites of domesticated animals. It seems possible that the other two species of parasites may not have been brought to your notice. Both of these, namely, the “masuri” and the “soorti,” are very common in elephants. They are both found in the intestines only. The “masuri,” when present in any quantity, cause considerable disturbance, and the animal instinctively resorts to the eating of earth, which it consumes in large quantities until the bowels are acted on and the worm expelled. The soorti is more common than masuri, and does not seem to inconvenience the animal very much. When expelled from the animal the soorti is a round white worm, like most of the threadworms; the masuri, on the other hand, is of a delicate flesh color.” Shortly after the receipt of this letter I obtained the entozoa in a good state of preservation. Accordingly I wrote to General Hawkes, stating that the flukes were clearly referable to Fasciola Jacksoni; that the parasites to which the natives of Hindostan apply the term “soorti” were evidently examples of Ascaris lonchoptera (Diesing), previously called strongyles by Rudolphi; and that the worms which he called “masuri” were trematodes new to science. I named the species Amphistoma Hawkesii, in honor of the donor. The bottle contained as many as forty-nine specimens. I may here remark that I have made inquiries of the keepers of the elephants at the Zoological Gardens as to whether they have ever seen entozoa that were passed by the animals under their care. They replied in the negative, the keeper of the African elephants (Scott) having made frequent inspection of the fæces. I was the more anxious to secure information on this point since, during my frequent visits to the menagerie, I had observed that the African elephants were in the habit of swallowing large quantities of mud and dirt from small hollows in the ground near the great water-tanks in which they bathe. Prof. Garrod (who had dissected three elephants) also assures me that there has been no trace of an entozoon in any of the Indian elephants examined by him. In one dissected at Edinburgh the same negative result was obtained. From the facts at present in my possession, I conclude that the habit of earth-eating, displayed alike by Indian and African elephants (and, as stated in my account of the equine parasites, shared by horses), is not necessarily due to the presence of parasites. I apprehend rather, that it is resorted to by these animals under any circumstances of intestinal irritation, whether created by entozoa or other foreign agents. The notion of the elephant’s intelligent self-cure by eating earth is a very old fable. Captain Forsyth, as quoted by Mr Fleming, alludes to it in his ‘Highlands of Central India,’ and I find the same ideas recorded by Williamson and Howitt. Forsyth says:—“Elephants are very liable to intestinal worms. They generally cure themselves by swallowing from ten to twenty pounds of earth.” Captain Williamson says:—“They are much troubled with worms, for the cure of which the elephant eats earth. If the dung be inspected there will be seen an amazing number of moving objects, which much resemble pieces of chewed sugar-cane.” Some excellent practical remarks are added, testifying to the value of the native remedy called Kallah-nimok, or bit-noben, which is a saline purgative. In Lieut. Ouchterlony’s essay (quoted below) no allusion is made to the subject of worms.

General Hawkes afterwards supplied me with further information. In a letter from Secunderabad, dated July 30th, 1875, he says:—“As regards the liver-fluke (F. Jacksoni), it appears from your treatise to have been first observed in 1847. The only other published notice that I have been able to find of it is contained in a letter to a newspaper, dated ‘Rangoon, 16th July, 1867,’ and is signed ‘R. B.’ In this letter the unusual mortality of seven elephants in about fifteen days is attributed to the presence of this liver-fluke, the two other parasites (Amphistoma and Ascaris lonchoptera) being also present in the intestines.” “Now (continues General Hawkes), in every case at which I was present flukes were found in greater or less numbers in the gall-ducts of the liver, and the Amphistoma was also as constantly present in the intestines, the soorti (Ascaris lonchoptera), contrary to the general experience of the elephant attendants, being less frequently met with, though from its color and slender shape it is not so easily detected among the huge mass of fæces as the larger Amphistoma.” Speaking of the amphistoma General Hawkes says:—“This internal parasite is well known to all who possess elephants. It is alluded to by Dr Gilchrist in his treatise on the ‘Diseases of Elephants,’ first published in 1841, but he merely mentioned it under its local name, masuri, and made no attempt either to describe it scientifically or to ascertain its place in the natural system. As far as my experience goes it is only found in the intestines. These parasites appear to be very generally present in the elephant. When their numbers are few the ‘host’ is probably not much inconvenienced, but when present in any great quantity they undoubtedly cause much irritation. When this is felt, the animal, as before remarked, instinctively resorts to a simple and effectual remedy. He eats a quantity of earth, which purges him thoroughly and expels the amphistoma. The mahawats are of opinion that whilst the elephant is eating earth to relieve himself of the pests the daily allowance of rice should be scrupulously withheld; and they say that if the rice, which is given uncooked, is eaten by the animal under these circumstances, excessive purgation is induced, which frequently results in death. How far this opinion is founded on fact I am unable to say, but the mahawat’s name for this disease means ‘fasting,’ and bears testimony to the generally received notion of the necessity of withholding the rice when the animal is eating earth.”

When describing the parasites of the horse (p. [358]), I spoke of Collins’ amphistome from that animal, but in the letter addressed to me from Simla, 22nd March, 1875, Mr. Collins made no allusion to the earth-eating habit. He wrote:—“I forward you by this mail parasites found in the colon of a horse that died, a subject of fever peculiar to this country. There were about a thousand of the parasites, and nearly the whole of them were situated close to the cæcum, and were loose in the gut. Not having seen parasites at all similar to these, I have forwarded them for identification. They were of a brick-red color when first obtained.” These explicit statements by Mr Collins are interesting from many points of view. One has only to place his specimens side by side with those from the elephant in order to satisfy one’s self that the two forms are distinct. For the reasons already stated I provisionally called the worm Amphistoma Collinsii. It is probable that other veterinary surgeons have encountered this entozoon in India; but, unless they can point to some published account of the fact, Mr Collins is entitled to be considered as its discoverer. Doubtless many other European residents in India, Ceylon, and Burmah, must, like Dr Gilchrist, be well acquainted with the masuri as such, though unaware of their zoological position.

In a record of the post-mortem examination of one of the victims of the Secunderabad epizoöty, the veterinary surgeon said:—“No doubt disease of the lungs and subacute inflammation of the bowels were the immediate cause of death, but the large number of flukes in the liver and the intestinal parasites (i.e. the amphistomes) account in a great measure for some of the symptoms shown, and these symptoms accord in many respects with those shown in elephants that died in Burmah during the epizoöty (rot) in 1867, as recorded by R. B., notably, refusal of food, standing with mouth open, restlessness, and puffiness about the head and shoulders. The liver parasite is no doubt the same referred to by R. B., and is that termed by Dr Cobbold Fasciola Jacksoni.” In reference to a later case the same officer remarks:—“I carried out the post-mortem examination with special reference to inquiry as to the probability of the mortality amongst elephants at this station being of parasitic origin. This was suggested to me by the former case. The post-mortem appearances differed in every respect. There were flukes in the liver, but in no great quantity, and the structure of the liver was sound. Although not assisted by this case in attributing the mortality to parasitic origin, I am strengthened in my opinion that the death of the previous elephant was due to disease caused by the presence of the liver fluke.” This report, by Mr W. S. Adams, is to some extent in harmony with later information. An epizoötic outbreak amongst elephants has occurred in England, at Sanger’s Circus, and I had opportunity to examine one of the dead animals. In my own opinion, and in that of Mr F. Smith, the veterinary surgeon who attended the animals professionally, the disease was due to parasites. I obtained large quantities of Amphistoma Hawkesii from the intestinal canal, and also other worms. The death of one of the elephants was made the subject of litigation, when, as might be expected, great diversity of opinion as to the cause of the fatal issue prevailed.

Mr Smith, an old pupil of mine, regarding the amphistomes and strongyles as the cause of death, wrote to the effect that “some of the worms were found between the coats of the intestine, and others on the free surface of the gut, whilst the excretory ducts of some of the glands were found blocked with them.” The animal examined by myself on the 24th of August, 1876, yielded numerous examples of Amphistoma Hawkesii, Ascaris lonchoptera, and Dochmius Sangeri, the last species being so named by me after the owner of the circus who lost the herd of elephants by the epizoöty. The male Dochmii measured 5/8 and the females 3/4 of an inch in length. Here I must reluctantly quit the helminths of elephants, adding only an expression of surprise that Dr Max Schmidt should have had so little to say concerning them in his otherwise instructive memoir on ‘The Diseases of Pachyderms’ (quoted below).

I have but a few words to offer respecting the ectozoa. A species of mite has been described whose generic position appears doubtful. I allude to Homopus elephantis of Fürstenberg, or Symbiotes elephantis of Gerlach. According to Mégnin it is a nymphe adventive or hypope of a variety of Tyroglyphus siro. This acarus is abundant in old forage. Another ectozoon is Hæmatomyzus elephantis. It differs from the lice proper in many respects, but, according to Piaget, the reproductive organs resemble those of Hæmatopinus. In ‘Science Gossip’ for June, 1871, Mr H. C. Richter describes “a new form of parasite,” which is called Idolocoris elephantis. The insect, which was one line in length, was found upon an elephant in Ceylon. According to Walker it not only constituted the type of a new genus, but of an altogether new family of the Hemiptera Heteroptera, coming very near to the bed-bugs (Acanthidæ). It is a huge sucking louse. From the discussion which followed, it seems that the parasite had several times been seen before, and was none other than E. Piaget’s Hæmatomyzus elephantis. Excellent figures accompany Richter’s and Piaget’s descriptions. Notwithstanding Piaget’s explanation, I think the specific name, longirostris, would have been a more appropriate appellation.

Bibliography (No. 51).—(Anonymous), “Diseased Elephants,” see ‘Lancet,’ Sept. 2, 1876; also “Report of the Case at Law (Jamrach v. Sanger),” given in the ‘Veterinarian,’ Dec., 1877, p. 886.—Cobbold, T. S., “Description of a species of Trematode from the Indian Elephant, with remarks on its Affinities,” ‘Quart. Micros. Journ.,’ Jan., 1869; see also ‘Entozoa,’ supp., 1869, p. 80.—Idem, “On the Destruction of Elephants by Parasites, with remarks on two new species of Entozoa and on the so-called Earth-eating habits of Elephants and Horses in India,” ‘Veterinarian,’ Oct., 1875.—Idem, “Further Remarks on Parasites from the Horse and Elephant, with a notice of new Amphistomes from the Ox,” ibid., Nov., 1875.—Diesing (l. c., in text).—Fitz, R. H., “Anatomy of Fasciola Jacksoni,” ‘Rep. of Boston Soc. Med. Sci.,’ in the ‘New York Med. Journ.,’ Nov., 1876.—Fleming, G., “The Diseases of Elephants” (chiefly from Captain Forsyth’s work on the ‘Highlands of Central India’), ‘Veterinarian,’ March, 1873, p. 181.—Mégnin, “Mém. sur les Hypopes,” in Robin’s ‘Journ. de l’Anat. et de la Physiol.,’ 1874 (H. elephantis), p. 248.—Ouchterlony, J. W., “An Essay on the Management of the Elephant, and its Treatment in ordinary Diseases,” ‘Rep. of Vet. Med. Assoc.,’ Nov., 1872, and pub. in ‘Veterinarian,’ Jan., 1873, p. 65.—Piaget, E., “Description d’un parasite de l’éléphant,” ‘Tijschrift voor Entomologie,’ 1869, p. 249.—Richter, H. C., “A new form of Parasite (Idolocoris elephantis),” ‘Science Gossip,’ 1871, pp. 131, 185, 211, 278.—Schmidt, Max, “Die Krankheiten der Dickhäuter,” ‘Deutsche Zeitschrift f. Thiermed. und vergleichende Pathologie,’ f. Nov., 1878, s. 360.—Williamson, T., ‘Oriental Field Sports,’ London, 1807, vol. i, p. 138.

The parasites of the Rhinoceridæ have been even less studied than those of elephants. In 1856 Prof. Peters described a tapeworm from Bruce’s rhinoceros (R. Africanus), which he named Tænia gigantea. In 1870 Dr Murie, under the provisional name of T. magna, published a description of the strobile of the same cestode from an Indian rhinoceros (R. unicornis). From a total misconception of the character of the proglottides, Murie was led to suppose that the segments of the strobile were very deep as well as broad; whereas the proglottids are remarkably narrow, thus partaking of the characters of the Tæniæ of the larger herbivora in general. In a subsequent paper Peters pointed out these errors. Murie had, in fact, rolled several segments into one. In 1877 Professor Garrod encountered the same cestode in Rhinoceros sondaicus, and, following Peters’ example, separated it from the Tæniæ proper (Plagiotænia gigantea). The idea of generically separating tapeworms possessing a more or less striking breadth of strobile is not one which commends itself to my view, seeing that many of the tapeworms of herbivora closely resemble the rhinoscerine cestodes in this respect. As Diesing hints, this tapeworm comes near to T. perfoliata, but Garrod’s and Peters’ figures both show that Plagiotænia wants the neck-lobes. The presence of cephalic appendages may be regarded as generically distinctive, but it does not appear that Blanchard separated the perfoliate tapeworm of the horse from the Tæniæ proper on this ground. Therefore, in my account of the equine tapeworms, I have not adopted his genus Anoplocephala. I may remark, in passing, that if the distinctions, as between armed and unarmed, or between proboscis-bearing (Rhynchotæniada) and non-proboscis-bearing tapeworms (Arhynchotæniada), are to be maintained, they should be expressive of divisional or subordinate value. Dr Weinland’s arrangement, having reference to the thick- and thin-shelled ova (Sclero- and Malaco-leptidota), is, perhaps, preferable. The whole subject of classification requires revision, but it should be undertaken by some helminthologists practically acquainted with a large number of cestode types. As Garrod has well observed, Plagiotænia enjoys a wide geographical distribution, infesting alike Indian and African hosts. Prof. Garrod, I observe, speaks of the head of the mature tapeworm as the scolex—an extension of the meaning of a term not usually recognised. In this, however, he only follows Peters’ unfortunate example.

The wide distribution enjoyed by Peters’ Plagiotænia is probably equalled by that of the rhinocerine stomach-bot (Gastrophilus rhinocerontis, Owen). This parasite was originally described in 1840, and since that time it has been frequently encountered both in India and Africa. To Mr Spooner Hart, of Calcutta, I am indebted for a large number of specimens; their size exceeding that of any other bots that have come under my notice. Probably this parasite infests the stomach of rhinoceroses generally; at all events, it occurs in R. unicornis, R. bicornis, and R. simus. At present the imago is unknown. The longest larvæ in my possession measure 11/8″, but Brauer records specimens up to 35 mm. in length by 10 mm. in thickness. In African hosts M. Delegorgue found these parasites in prodigious numbers.

Bibliography (No. 52).—Brauer, “Bot of the Rhinoceros,” ‘Monogr. der Œstr.,’ 1863, s. 92.—Cobbold, “Note on Parasites presented by Messrs Danford, Hart, and others,” ‘Veterinarian,’ 1875, p. 513.—Coquerel and Sallé, in ‘Ann. Soc. Entom. de France,’ 1862 (quoted by Brauer).—Delegorgue, ‘Voyage dans l’Afrique’ (quoted by Brauer).—Garrod, “On the Tænia of the Rhinoceros of the Sunderbunds (Plag. gig., Peters),” ‘Proc. Zool. Soc.,’ Nov. 20, 1877, p. 788.—Hope, in ‘Trans. Entom. Soc.,’ 1840, p. 259.—Joly, M. N., “Recherches Zool. (&c.) sur les Œstrides (&c.),” in ‘Ann. des Sciences (&c.) de Lyon,’ 1846 (quoted by Brauer).—Murie, J., “On a probably new species of Tænia (T. magna?) from the Rhinoceros,” ‘Proc. Zool. Soc.,’ 1870, p. 608.—Peters, W., “Note on the Tænia from the Rhinoceros, lately described by Dr J. Murie,” ‘Proc. Zool. Soc.,’ 1871, p. 146.

Very little has been written respecting the parasites of the Hippopotamidæ and Tapiridæ. I think it was Livingstone who first drew attention to the fact that the river-horse or sea-cow is much infested by tapeworms, but I have not seen any published description of the worm. Dr Murie, during his sojourn in Egypt, found a solitary bot embedded in the soft parts surrounding the eye, and judging from his figure the species is new to science. Provisionally I speak of it as the Hypoderma Muriei. In the paper (quoted below) Murie appends a list of all the animals in which bots have been found. Though chiefly taken from Brauer, it is useful and tolerably complete. So far as I am aware no cestodes have been described as infesting tapirs; nevertheless, at least five other kinds of helminth have been found in Tapirus Americanus. Of these, two are flukes (Amphistoma asperum and A. pyriforme), and three are nematodes (Sclerostoma monostechum, Spiroptera mediospiralis, and Sp. chrysoptera). The three species first named occupy the cæcum, whilst the others are found in the stomach. According to Molin’s description, both species occupy tuberous excrescences of the mucous membrane, thus reminding us of the similar habit enjoyed by Sp. megastoma in the horse. The Sp. chrysoptera is a comparatively large species, the males measuring an inch, and the females as much as an inch and a half in length. Both of the spiropteras were obtained from tapirs by the indefatigable Natterer, Sp. mediospiralis being also procured by him from the aguti. If I have read Molin correctly, as many as thirty-four examples of S. mediospiralis were taken from a single excrescence in the stomach of the tapir. Upwards of a hundred specimens were procured, collectively, from three similar stomach-excrescences in Dasyprocta aguti. These, and the other tapirine parasites above mentioned, were originally discovered in Brazil.

Bibliography (No. 53).—Diesing, “Neue Gattungen von Binnenwürmen nebst einem Nachtrage zur Monographie der Amphistomen,” in ‘Annalen d. Wien. Museums,’ Feb., 1839, s. 236.—Idem, ‘Systema,’ Bd. ii, s. 306.—Molin, “Una monografia del genere Spiroptera,” in ‘Sitzungsb. der math.-naturw. Cl. d. k. Akad. d. Wissensch.,’ Bd. xxxviii, s. 1001, 1859.—Murie, “On a larval Œstrus found in the Hippopotamus,” ‘Proc. Zool. Soc.,’ 1870, p. 78.

The osculant position of the anisodactyle pachyderms (Hyracidæ), formerly classed as rodents, renders it desirable that their parasites should be briefly noticed in this place. Probably these animals, zoologically speaking, come nearest to the rhinoceroses, but Prof. Owen showed that, anatomically, they possessed marked affinities with the sloths. The klipdas or dasse (Hyrax capensis) is infested by a tapeworm, of which hitherto the proglottides only appear to have been seen (Tænia hyracis, Pallas). Under the name of Cœnurus serialis a larval cestode has been described by Gervais, the same parasite being called Arhynchotænia critica by Pagenstecher (“Zur Naturgeschichte der Cestoden,” in ‘Sieb. u. Köll. Zeitschrift’). A variety of nematodes have also been observed in the Cape hyrax. Of these, the so-called Physaloptera spirula is classed as doubtful by Molin and Diesing. Hemprich and Ehrenberg furnished brief descriptions of four other nematodes. Two of these worms were placed in the genus Oxyuris (O. pugio and O. flavellum), and the other two in the new genus Crossophorus, which they formed for their reception (C. collaris and C. tentaculatus). The whole of these nematoids were obtained either from the cæcum or large intestine.

An able article in the ‘Natural History Review’ for July 1865, attributed to Professor Huxley, expressed very clearly the popular notion as to the great danger of the flesh of swine considered as a source of human parasites. No doubt the filthy pachyderms in question (Suidæ) are much infested by helminths, some of which gain access to man, but swine are neither attacked by a greater variety of entozoa than other domesticated animals, nor are they so frequently a source of human tapeworms as cattle. In the article above quoted the following passage occurs:—“Of all animals, feral or domestic, the common pig is beyond all doubt the most fertile source of human entozoa; at least, of important parasites, Trichina spiralis and the tapeworm would, there is good reason to believe, cease to infest us, did not this favorite quadruped act the part of a communicating medium.” This paragraph was evidently written under the impression that “the tapeworm” most commonly found in man was derived from the hog. So far back as 1864 I showed that this was an entire mistake.

Fig. 66.—Head and neck of Cysticercus from the Red River hog. Magnified 60 diameters. Original.

Flukes are rare in swine; nevertheless, Fasciola hepatica and Distoma lanceolatum are occasionally present in the domestic hog, and the peccaries (Dicotyles) are infested by an Amphistome (A. giganteum). This large species, 3/4″ in length, formed the basis of an admirable account of the anatomy of this genus of worms which the learned Vienna helminthologist, Diesing, wrote before he was deprived of his eyesight. The merits of that respected systematist’s investigations have, I think, been much underrated, in consequence, no doubt, of the artificial character of his system of classification. For all that, his writings remain invaluable. Turning to the cestodes of swine, there is not, so far as I am aware, any evidence of the occurrence of sexually-mature tapeworms either in the hog or its allies; but the frequency of larval cestodes, known as measles (Cysticercus telæ cellulosæ), was well known to the early Jewish writers. In the first part of this work I devoted as much space as I could spare to the consideration of Cysticerci in general, and the pork-measle in particular; but an exhaustive knowledge of the subject in relation to hygiene can only be acquired by consulting the principal original memoirs (quoted in the Bibliographies Nos. [13] and [14]). In a Westphalian ham, part of which was sent to me for examination, I calculated that each pound of the flesh must have contained upwards of 600 Cysticerci. I was informed by the donor, Dr Prior, that in spite of the disgusting state of the meat much of it had been eaten by the well-to-do family who purchased the ham. Cysticerci occasionally occupy the brain of the pig in considerable numbers. Florman recorded a case of this kind where their presence gave rise to vertigo in all respects resembling the gid ordinarily produced by Cœnurus in the sheep. As regards the larger cestode larvæ, Cysticercus tenuicollis and Echinococcus veterinorum are of frequent occurrence. One not unfrequently encounters the former in the mesentery, whilst the liver of the hog is sometimes so crowded with hydatids that scarcely any of the glandular substance of the organ remains visible. It is surprising how little the infested bearers appear to be inconvenienced in such cases. In the winter of 1859, and in the autumn of 1860, I found large cystic entozoa in an African Wart-hog and in a Red River hog. These animals had died at the London Zoological Society’s Menagerie; and as the worms appeared to me at the time to be quite distinct from the ordinary slender-necked hydatid, they were named, respectively, Cysticercus phacochæri æthiopici and C. potamochæri penicillati. The solitary example from the wart-hog was found in a cyst near the colon; whilst of the five large bladder-worms obtained from the Red River hog, one infested the liver and the other four were lodged in the folds of the mesentery. The caudal vesicle of the worm from the wart-hog measured 31/2″ in diameter, the vesicle of the other bladder-worm being much longer. A reference to the original figures will show that these forms are distinct. Swine are largely infested by nematodes. The best-known form is Ascaris lumbricoides, which Dujardin regarded as distinct (A. suilla). The hitherto disputed identity of this worm with the human lumbricoid being no longer questionable, the importance of the entozoon in relation to lumbricoid endemics must at once be obvious; I have already, however, dwelt upon this subject when treating of the human parasites. In like manner, the subject of the flesh-worm disease, which is due to Trichina spiralis, cannot be discussed in this place, as I have fully entered upon it in connection with trichinosis in the human subject. What may be the nature of the small threadworms found by Leidy in the extensor muscles of the hog I cannot say, but Diesing inferred that they might represent a distinct species (Trichina affinis). As regards the allied genus Trichocephalus, the common species infesting swine (T. crenatus), appears to be rarely absent. It not only infests the common domestic and wild hog, but the peccaries and wart-hogs. These entozoa are probably harmless to their bearers. In reference to them Krabbe says:—“When the eggs are expelled with the excrement and pass into water, then the embryos, after several months’ furlough, and there undergoing further development, are transferred to the swine’s intestinal canal.” If I rightly understand the paragraph (‘Husdyrenes Indvoldsorme,’ p. 28), Krabbe states that the embryos are still within their egg-coverings when infection takes place. The maw-worm of the hog is known as Spiroptera strongylina. It was described and figured by Gurlt. The males measure 1/2″ and the females 3/4″ in length. Specimens of this worm were supposed to have been found by Natterer in Dicotyles albirostris; but it seems that the worms in question represent a distinct species, if not an altogether new genus. In the year 1864 Professor Simonds placed in my hands a very singular nematode, to which I gave the binomial term Simondsia paradoxa. Numerous examples of this worm were found by Prof. Simonds occupying cysts within the walls of the stomach of a hog which had died at the London Zoological Society’s Menagerie. In my introductory treatise I wrote of it as follows:—“The worm in question has been regarded by Mr Simonds as a species of Strongylus, but I am inclined to think that its affinities will place it nearer to the genus Spiroptera. At present I have only examined the female, which is characterised by the possession of a multitude of large tentacle-like appendages surrounding the neck. These processes, by their aspect, remind one of the so-called branchial projections on the back of Eolis, but in this worm I believe them to be special folds formed for the lodgment of unusually developed uterine organs. The female worm is about 3/4″ in length.”

In the interval that has elapsed I have been unable to supply further particulars, and unfortunately the original drawings of the worm have been lost. The habits of the parasite remind us of Spiroptera megastoma infesting the walls of the stomach of the horse. Not improbably this singular entozoon may turn out to be identical with Molin’s Spiroptera sexalata, and if so, it may correspond with Spiroptera strongylina. However, Diesing afterwards recognising, as I had done, the desirability of separating this last-named worm from the Spiropteræ proper, formed for it his new genus Physocephalus. He then called the worm Physocephalus sexalatus. If, as is probable, my Simondsia and Diesing’s Physocephalus are identical, the species found by Simonds ought to be recognised by the generic title which Diesing proposed. His genus was established about four years before I described my Simondsia. Diesing was evidently led up to the recognition of the generic distinction of the worm by Molin’s examination and description of the worm. As, in my original account of the worm found by Simonds, I spoke of numerous appendages to the neck, it is evident that further investigation is necessary to clear up the question of identity. According to Molin and Diesing the male Spiroptera sexalata measures rather beyond 1/4″ and the female beyond 1/2″ in length. Neither Diesing nor Molin speak of Natterer’s worms as being found encysted. In fact they were free. Molin simply remarks:—“Io ne esaminai in oltre 6 esemplari maschi e 77 femine raccolti in parte dal muco che revestiva le pareti dello stomaco, ed in parte dal pasto contenuto nello stesso organo di un Dicotyles albirostris femina ai 24 Aprile, 1826.” After all that has been said it may be that my Simondsia paradoxa and Diesing’s Physocephalus sexalata are quite distinct, and that like the large- and small-mouthed maw-worms of the horse (Spiroptera megastoma and S. microstoma) they play a corresponding rôle. Before very long I hope to set this question definitively at rest.

Passing to the strongyloid nematodes one of the most remarkable and important species is Stephanurus dentatus. In the ‘Annalen des Wiener Museums’ for 1839 (s. 232) this worm was first described by Diesing, who employed the generic title as expressive of the crown-like figure of the tail of the male worm. Diesing wrote as follows:—“At Barra do Rio Negro, on the 24th of March, 1834, Natterer discovered this peculiar genus of worms occurring singly or several together in capsules situated amongst the layers of fat in a Chinese race of Sus scrofa domestica. The males measure from ten to thirteen lines long, the females from fifteen to eighteen lines, the former being scarcely a line in breadth at the middle of the body, whilst the latter are almost a line and a half in thickness. The curved body thickens towards the tail, is transversely annulated, and viewed with a penetrating lens is seen to be furnished with integumentary pores. The oral aperture opens widely. It is almost circular, and is supplied with six teeth at the margin. Two of these standing opposed to one another are larger and stronger than the rest. The tail of the male, when spread out evenly, is surrounded by a coronet of five lancet-shaped flaps; the combined flaps being connected together from base to apex by means of a delicate transparent membrane. The single spiculum situated at the extreme end of the tail projects slightly forward and is surrounded by three skittle-shaped bodies. The tail of the female is curved upon itself, rounded off, and drawn out at the extreme end into a straight beak-shaped point; whilst to both sides of the stumpy caudal extremity of the body short vesicular prominences are attached. The female reproductive outlet occurs at the commencement of the second half of the body. Thus, judging by its external characters this genus is most closely allied to Strongylus.” In reproducing Diesing’s description I have here rendered the translation somewhat more freely than in my previous record of the discovery given in ‘Nature’ (1871). The original description is supplemented by a brief account of the internal anatomy of the worm.

So far as I am aware no subsequent notice of this entozoon appeared until the year 1858, when Dr J. C. White gave some account of a “find” made in the United States. This re-discovery was reported in the sixth volume of the ‘Proceedings of the Boston Natural History Society.’ Dr White says:—“The worms were found in the leaf-yard of an apparently healthy hog, in the adipose tissue near the kidney. They occupied a space of the same about the size of a man’s fist and had burrowed through the mass in every direction, forming canals three or four millimètres in diameter, which terminated in cysts. On cutting open these cavities, which did not communicate with each other, they were found filled with pus, and in each were two worms, male and female.” Dr White expresses his opinion that the worms gained access to the tissues “by boring through the circulatory system while in the embryonic condition.” I think that Dr White deserves great credit for his correct diagnosis of the species, and all the more so because he was evidently not acquainted with Diesing’s original memoir. He expressly speaks of the “scanty descriptions” hitherto given of the worm. As Dr White had accurately determined the species in the presence of an American Scientific Society, it is remarkable that neither Verrill nor Fletcher should have identified the worm.

On the 10th of January, 1871, I received a letter from Prof. W. B. Fletcher, of Indianapolis, Indiana, U.S.A., and in it he announced that he had “found a worm” infesting the hog. The parasite was so abundant in swine that he obtained it in “nine out of ten hogs” which he had examined. Dr Fletcher sent me specimens of the worm for description and identification, when I at once recognised them as examples of Diesing’s Stephanurus dentatus. As Dr Fletcher’s first communication to myself was undated I do not know precisely when he first encountered the worm, but it was in 1870. In that same year Prof. Verrill received specimens of the worm. He says that they were received from Dr J. C. White. Failing to identify the parasites as Stephanuri, Verrill (making no allusion to the ‘Proceedings of the Boston Society’) not unnaturally supposed he had to deal with an entozoon that was new to science. Accordingly he immediately described and figured the worm under the combined title of Sclerostoma pinguicola. If these data are correctly given, the re-discovery of the worm in America was due to Dr J. C. White; its identity with Stephanurus being subsequently acknowledged by Diesing, and afterwards, quite independently, by myself. I gather this partly from Diesing’s ‘Kleine helminthologische Mittheilungen’ (s. 281), published as a supplement to his ‘Revision der Nematoden’ (1860–61). Until quite recently Diesing’s recognition of the identity of White’s parasites with Stephanuri was unknown in America. My conclusions arose from an examination of the actual specimens, whereas Diesing was entirely guided by White’s description. In this connection, moreover, a still more interesting re-discovery remained to be recorded. The original announcement which I made in the ‘British Medical Journal’ for January 14th, 1871, was followed by another in the same periodical for September, 1871. As stated in my second letter and repeated in my notice of Krabbe’s memoir on “Parasites” (‘London Medical Record,’ April 2, 1873), the President of the London Microscopical Society (through Mr Slack, who was at that time the secretary) forwarded to me a box of microscopic slides received by the Society from Australia. The slides displayed parasites of various kinds. Having been requested to identify the parasites I had the good fortune to recognise amongst them characteristic examples of Stephanurus dentatus. Thus was first made known the fact that this singular genus was not confined in its geographical distribution to the two American continents, but that it extended to Australia. The order of the principal “finds” and descriptions may therefore be thus restated. Natterer discovered the worm in Brazil in 1834. Diesing described it in 1839. Dr J. C. White re-discovered and identified the worm in 1858. It was subsequently found by Dr N. Cressy and by Dr Fletcher. These three observers all encountered the parasite in the United States (1858–70). Prof. Verrill re-described the worm as new to science in September, 1870. Diesing confirmed White’s diagnosis in 1860. I identified the worm from Fletcher’s “find” in 1871. Dr Morris supposed he had discovered a new entozoon in Australia in July, 1871. The Australian worms were identified by me as examples of Stephanurus dentatus in October, 1871.

The importance of Stephanurus in relation to porcine epizoöty and the supply of animal food cannot be ignored. As remarked in my communication to ‘Nature,’ it must be quite obvious that so large a parasite, when present in the hog in any considerable numbers, would give rise to serious disease, even if it were not productive of fatal results to the bearer. In one of his numerous communications to myself, Prof. W. B. Fletcher writes as follows:—“It is my opinion that this parasite is the cause, in some way, of the hog cholera, which has created such sad havoc within the past ten years over the pork-producing parts of America. One farmer told me, a few days ago, that within a month his loss alone from this cause was over one hundred head; and sometimes, in one neighbourhood, in a few days’ time, thousands have perished, although this season is not a cholera year, as our farmers say. I advised one farmer to burn or bury the dead animals, but he informed me that he believed that fewer hogs die of the disease after eating the dead animals than those kept from them. Unfortunately, in this State there is no law guarding the spread of disease, neither is there any reward of reputation or gain for pursuing any investigation that would bring pork and beef packers into disrepute. I myself could not get a pig’s kidney or beef’s liver in our city market, because I made investigations in some Texas cattle (being cut up in our market), which damaged their sale a few years ago.” In a third letter Dr Fletcher tells me that greater facilities for examining the carcases of hogs had since been accorded him through the liberality of a Liverpool firm of pork-packers, who had already killed 75,000 hogs during the summer season, i.e. up to the date of the first week in July. In hot weather the slaughtering is conducted in ice-houses. Prof. Fletcher’s views receive confirmation from the statements made by Dr Morris, who speaks of the pigs as dying from some mysterious disease, and thinks that the worms may be the cause of the porcine mortality. Writing to the President of the London Microscopical Society from Sydney (July 12th, 1871), Dr Morris says:—“It is just possible that some pigs may survive the irritation such a swarm of young worms must set up; others, again, may die from peritonitis, hence the sudden deaths amongst the pigs.” I think Dr Morris’ view is perfectly correct, but whether it be so or not, it is (as observed by me in ‘Nature’) interesting to notice the remarkable correspondency of the conclusions arrived at by Drs Fletcher and Morris independently. It will probably not be difficult to ascertain hereafter whether or not the maladies respectively termed “hog cholera” and “mysterious disease” are one and the same disorder, but whatever happens in this respect, it is now quite clear that this parasite, hitherto little regarded, and for many years past persistently overlooked, is extraordinarily prevalent in the United States, and, perhaps, equally so in Australia; it being further evident that its presence in the flesh of swine is capable of producing both disease and death. The statement of the worthy American farmer that the swallowing of infested flesh by pigs does not necessarily involve the pig-eating hog in a bad attack of the so-called “cholera disease” requires to be further tested, and it also remains to be proven whether or not the Stephanurus be capable of passing through all its developmental changes from the egg to the adult form within the body of the bearer without having at some time or other gained access to the outer world. The comparatively large size of the ova, which I find to be about 1/105″, or more than four times the size of Trichina-eggs, is not without significance, but as yet we are entirely unacquainted with the larvæ of Stephanurus. If no intermediary bearers are necessary to its development, we ought not to have to wait long for a complete record of the life-history of Stephanurus dentatus. In conclusion, I will only further remark that since thousands of hogs are infested by this entozoon the subject is worth further investigation. I believe that Prof. Fletcher brought the matter under the notice of the United States National Swine Breeder’s Association, which met at Indianapolis in November, 1872, but with what success I have been unable to learn. The wealthy agricultural societies of Great Britain pay little or no regard to the subject of parasites, although thousands of valuable animals annually perish from the injurious action of entozoa.

Of the remaining nematodes infesting swine I must particularly mention Sclerostoma (Strongylus) dentatum and Strongylus paradoxus, the last named being generally regarded as identical with Dujardin’s S. elongatus. The first of these two parasites infests the small intestines, the male and female worms alike measuring about 1/2″ in length. The females are sometimes a trifle longer. The Sclerostoma dentatum is an abundant parasite, infesting all varieties of swine and also peccaries; but it is apparently incapable of serious injury to the bearer. Schneider selected the male S. dentatum for classificatory purposes. In this worm the arrangement of the rays of the hood is simple, forming a good central type. Dr D. V. Dean, in his excellent report of St Louis Board of Health (1874), speaks of Strongylus dentatus as if it were the same entozoon as Stephanurus. The confusion of nomenclature would have been avoided if Diesing had called the renal worm Stephanurus Nattereri. I hope this title will yet be adopted to prevent future mistakes. The lung-worm (S. paradoxus) is by no means harmless, being a frequent cause of fatal husk in young pigs. It is a viviparous worm, the females acquiring a length of 11/2″, whilst the males rarely exceed 3/4″. Under the title Gongylonema pulchrum, Molin has noticed yet another filariform nematode infesting the wild hog; and, lastly, the lamented Russian traveller, Fedschenko, has published a full description of a new species of Gnathostoma (G. hispidum), which infests the coats of the stomach alike of the wild and domestic hog. One of the most interesting parasites of swine is the large acanthocephalous entozoon (Echinorhynchus gigas). It infests the small intestines both of the wild and domesticated hog, and it was also obtained by Natterer from the collared peccary of Tayazou. Common as the great Echinorhynchus is in the United States (and it is scarcely less so on the Continent) I believe that few, if any, of the museums in the United Kingdom of Great Britain contain this large entozoon. It is a curious fact that it does not exist in the Hunterian Collection, where, however, there is displayed a very fine set of acanthocephalous parasites from whales. When in the year 1865 I mounted, with my own hands, 200 preparations of entozoa for the Museum of the Royal College of Surgeons, I had not so much as seen a specimen of this worm. Much scientific interest attaches to this parasite from the fact that Schneider discovered that the embryos of E. gigas take up their residence in the larvæ of the cockchafer (Melolontha vulgaris). He thinks it identical with the Echinorhynchus hominis of Lambl. Leuckart disputes this identity, and compares Lambl’s worm with the Echinorhynchus angustatus of our fresh-water fishes. The E. spirula of certain Brazilian monkeys and of the Barbary ape bears a strong resemblance to the species from the hog. On the strength of Lambl’s case—and it is the only genuine instance of the kind on record—Prof. Leuckart devotes no less than 125 pages of his great work to the consideration of the structure and development of the thorn-headed intestinal worms. This worm demands especial attention. Speaking of the hog’s Echinorhynchus, Prof. Verrill, in his ‘Connecticut Report,’ says that “sometimes the intestine of a hog is found perforated by so many holes that it cannot be used in the manufacture of sausages.” From Mr George Wilkins I learn that the pig-slaughterers of our English metropolis are well acquainted with these perforations, which are sometimes so numerous that the gut looks as if it had been “riddled” with swan-shot. No wonder that diseased hogs, afflicted with these formidable parasites, go about, as Verrill expresses it, “continually squealing and grunting, especially in the morning.” That they are also “cross and morose, and given to biting and snarling at their companions,” is by no means astonishing. “In severe cases,” remarks Verrill, “hogs afflicted with this parasite are weak in the loins, and have the membranes in the corners of the eyes swollen, watery, and lighter colored than usual.” It is some comfort to know that Lambl’s human case is unique, and that so long as people abstain from eating cockchafer larvæ they are not likely to be infested by Echinorhynchus gigas. In the first book of this work I have given my reasons for not regarding Welch’s “encysted Echinorhynchus in man” as a genuine example of this curious genus of entozoa.

The external parasites of swine are not so numerous as might be expected from the habits of their hosts. The most common ectozoon is the hog louse (Hæmatopinus suis). This disgusting little insect is about 1/8″ in length. Almost equally common is the hog mite. Though hitherto considered as a distinct species (Sarcoptes suis, Gurlt), it is regarded by Mégnin as a mere variety of Sarcoptes scabiei. As Gerlach and others have remarked, it is readily transmissible to man. The Sarcoptes squammiferus, of Fürstenburg, is only another name for this variety of S. scabiei. Speaking of this scab-insect Mégnin says:—“This parasite was first encountered by Spinola and Gurlt, and afterwards by Müller.” He then adds:—“A Ceylon wild boar died at the menagerie of the Museum of Paris of a chronic affection of the skin which had transformed its integument into a vast lichen.” Lastly, as regards the protozoal parasites I can only remark that the psorosperms (spoken of as Rainey’s corpuscles or as Miescher’s utricles) are often very abundant in the flesh of otherwise perfectly healthy swine. Having dwelt upon the character of such organisms in the first moiety of this work, I will only remark that the full significance of these singular bodies yet remains to be determined. Rainey’s notion that they represented early stages of cysticercal growth is altogether untenable. According to Behrens, as quoted by Davaine, psorosperms are especially abundant in the flesh of swine which have recovered from the disease called mal rouge. On the subject generally, the writings of Rivolta, Waldenburg, Eimer, and Siedamagrotsky are especially trustworthy. Full references to these and other authorities are given in the synopsis of the 2nd edition of Davaine’s well-known treatise.

Bibliography (No. 54).—(Anonymous), “On Parasitic Maladies, especially Measles, of the Pig,” from ‘Scottish Farmer and Horticulturist,’ in ‘Edin. Vet. Rev.,’ p. 688, 1861.—Ballard, E., “On Diseased Meat, and what to observe in cases of suspected Poisoning by Meat or Sausages (infected with Entozoa, &c.),” ‘Med. Times and Gaz.,’ Jan., 1864.—Bowditch, H. J., “Raw Pork as an Aliment (without reference to the question of Entozoa.—T. S. C.),” ‘Boston Med. and Surg. Journ.,’ vol. lv, 1857; see also ‘Comments,’ vol. lvi, pp. 23 and 69, 1857.—Cobbold, “On the Discovery of Stephanurus in the United States and in Australia,” in ‘Nature,’ Oct. 21, 1871, p. 508, and in ‘Brit. Med. Journ.,’ Jan. and Sept., 1871; also in the ‘Monthly Micros. Journ.,’ Nov., 1871.—Idem, “Internal Parasites of the Hog,” in ‘Manual,’ chap. xii.—Idem, “On Cystic Entozoa from the Wart-Hog and Red River Hog,” ‘Proc. Zool. Soc.,’ 1861.—Idem, “On Simondsia,” ‘Entoz.,’ p. 79.—Idem, “Note on Worms in the Lungs of a Pig,” in the ‘Field’ for Jan. 9, 1864.—Idem (in relation to Cysticerci or Measles, see Bibl. Nos. [13] and [14], and, for remarks on psorosperms, Bibl. No. [41]).—Cressy, N., ‘On the Diseases of Domestic Animals in Connecticut (2nd and 3rd Ann. Reports),’ Hartford, U.S., 1873–74.—Idem, “The demands of Agriculture on Veterinary Science,” in ‘Rep. of the Mass. Board of Agric.,’ 1874.—Idem, ‘Find of Sclerostoma’ (quoted by Verrill).—Crisp, “Note on Hydatid Cysts in the Abdominal Cavity of various Hogs,” ‘Path. Soc. Trans.,’ 1863.—Dardel (see Bibl. No. [14]).—Davaine, “Ladrarie chez le porc,” in his ‘Traité,’ 2ème edit., p. 668 (see also the writings of Delpech, Guardia, and especially Reynal, quoted at p. 674).—Dean, D. V., “On Meats and Parasites,” in ‘Seventh Ann. Rep. of Board of Health of the City of St Louis,’ 1874, p. 58 et seq.—Diesing, ‘On Stephanurus’ (quoted in text above).—Dupuy, “Hydatid in a Pig,” from ‘Journ. Théorique et Prat.,’ in the ‘Veterinarian,’ vol. iv, 1831, p. 285.—Fedschenko, ‘Description of new Species of Tetrastemma, Prorhynchus, and Gnathostoma’ (in the Russian language), Moscow, 1872.—Fleming, A., “Measly Pork as Food for Man,” ‘Edin. Vet. Rev.,’ vol. i, p. 485, 1858–59.—Idem, “On the Measle of the Pig, and on the Wholesomeness, as Food for Man, of Measly Pork,” ‘Dubl. Quart. Journ.,’ 1857.—Fletcher (quoted in text above).—Florman (quoted by Rudolphi, ‘Synops.,’ p. 620, 1819; and by Davaine, l. c., p. 723, 1878), in ‘Vetensk. Acad. Nya Handlingar,’ 1810, pp. 179–182.—Gairdner, W. T., “Case of Tapeworm occurring in connection with the Eating of Raw Pork,” ‘Edin. Month. Journ.,’ 1856, and in the ‘Veterinarian,’ vol. xxix, p. 228, 1856.—Gamgee, J., “On Diseased Meat,” ‘Pop. Science Rev.,’ Jan., 1861.—Gordon, “On Tapeworm from Unwholesome Food,” ‘Med. Gaz.,’ 1857.—Gross, S. D., “Note on the frequency of Acephalocysts in Swine at Cincinnati,” in his ‘Elements of Path. Anat.,’ p. 118, 1845.—Gurlt, E. F., ‘Lehrbuch der path. Anat. der Haus-Saügethiere,’ 1831, s. 46, 51, 142, 385.—Heller (see Bibl. No. [13]).—Krabbe, ‘Husdyrenes Indvoldsorme’ (l. c., in text; see also review in ‘Lond. Med. Rec.,’ April 2, 1872, p. 206).—Leidy, “Note on Trichina spiralis from the Pig,” from ‘Rep. Acad. Philad.,’ in ‘Ann. Nat. Hist.,’ vol. xix, 1847.—Leuckart (see Bibl. No. [13]).—Lewis (Bibl. No. [13]).—Martin, J., “Case of Hydatids in the Liver of a Sow,” ‘Trans. Vet. Assoc.,’ pp. 330 and 364, 1842–43.—Mégnin (Bibl. No. [14]).—Molin, ‘Una Monog. del Gen. Spiroptera,’ Wien, 1860.—Morris, “Report on Australian Parasites,” ‘Month. Microsc. Journ.,’ Nov., 1871.—Percy, S. R., “On Diseased Meat in relation to Public Health (Prize Essay),” ‘New York Med. Journ.,’ 1866.—Idem, “On the Food of Cities (an Address),” ‘New York,’ 1864.—Perroncito (Bibl. No. [13]).—Putz (Bibl. No. [14]).—Rainey (Bibl. No. [14]).—Rigetti (Bibl. No. [14]).—Sawer, A., “Trichina,” in ‘Bost. Med. and Surg. Journ.,’ 1865, p. 16.—Schmidt, Max (see Bibl. No. [51]).—Tartivel (Bibl. No. [14]).—Thudichum (Bibl. No. [13]).—Tommasi (Bibl. No. [13]).—Verrill, “On Sclerostoma,” ‘Amer. Journ. Sci. and Arts,’ Sept., 1870.—Idem, “The External and Internal Parasites of Man and Domestic Animals,” from ‘Rep. of the Conn. Board of Agriculture,’ 1870, p. 109.—Walker (see Bibl. No. [20, o]).—Wheeler, E. G., “Worms in the Lungs of Swine,” ‘Bost. Med. and Surg. Journ.,’ 1841.—White, J. C., “On Stephanurus,” ‘Proc. Bost. Nat. Hist. Soc.,’ vol. vi, p. 428, 1858.