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.
Part XI (Cetacea).
The parasites of whales are excessively numerous. Unfortunately only a few of the species have been carefully studied, and much confusion necessarily exists as to the number of distinct forms. This statement is especially applicable to the entozoal group, which comprises upwards of a score of species. Probably Van Beneden has examined more of these parasites than any one else, and what little is known respecting them is for the most part due to his investigations. I have myself encountered and described several new species—a circumstance which Prof. Van Beneden appears to have altogether overlooked.
Fig. 67.—Distoma lancea. Original.
Commencing with the flukes, the first species I notice is Distoma lancea. The late C. M. Diesing’s description of this worm was based upon specimens obtained by Natterer in Brazil. The worms were discovered in the biliary ducts of a male dolphin dissected at Barra do Rio Negro on 29th December, 1833. Natterer calls this cetacean the tacuschi, and in a letter to Diesing names the species Delphinus tacuschi, in order to distinguish it from the D. amazonicus of Spix and Martius. Prof. Flower has shown that Spix and Martius’s D. amazonicus is referable to the inia or Bolivian dolphin (Inia Geoffroyi). The views of Flower, Natterer, and Diesing are thus far in agreement; and the geographical position of Barra shows that Natterer’s dolphin could not be the inia, since, as Blyth long ago remarked, this last named cetacean “inhabits only the remote tributaries of the Amazon and the elevated lakes of Peru.” Several other dolphins from Brazil have been described, one of which Mr Gray named Steno tacuxi. I think that Gray’s cetacean answers to the Delphinus tacuschi of Natterer; but Prof. Flower is of opinion that Gray’s species is an ordinary Delphinus. In this case it may, he thinks, probably be referred either to the D. fluviatilis or to D. pallidus. Whichever view is correct, it is clear that Natterer’s parasite was obtained from a fluviatile cetacean, and not from an oceanic or even an estuary form. In Diesing’s original description it is stated that Natterer found the Distoma lancea “once only,” when numerous examples were secured. To Dr Anderson I stand indebted for a solitary specimen, which he procured from the short-snouted dolphin (Orcella brevirostris, Owen). The obliging superintendent of the Calcutta Museum obtained this Distoma on the 3rd of January, 1873. He removed it from the duodenum, but it had probably escaped from the liver. Be that as it may, I easily recognised the species by the sinuosities of the margin of the body. Dr Anderson’s parasite does not exhibit these marginal irregularities so distinctly and sharply as they are shown in Diesing’s figures. Diesing remarks that the internal organs may be seen through the transparent body. The uterine organs, crowded with ova and of a purple color, are represented by him as branched after the fashion of a raceme. The artist has been misled. The uterine channel is not branched. Dr Anderson’s specimen showed two large oval testes placed one above the other in the middle line, and rather higher up than is usual with those distomes that have the organs presenting this simple form. The ducts were not visible. The yelk-forming glands were particularly well marked, consisting of two laterally-disposed masses, the left gland extending higher up than its fellow. The so-called yelk-cells or capsules were well seen. The oval-shaped eggs were tolerably distinct, yielding a length of 1/750″ from pole to pole, by about 1/900 in transverse diameter. The worm, when unrolled, did not exceed 1/6″ at most, whereas some of Natterer’s specimens measured 1/2″ in length. The neck had lost that rounded character which Diesing called skittle-shaped (kegelförmige). The ventral acetabulum is very nearly twice as large as the oral sucker. Diesing represents the ventral sucker as circular; but in Anderson’s specimen this organ was broadly oval.
Fig. 68.—Distoma Campula. Original.