Part IV (Evertebrata).
Fig. 85.—Sphærularia bombi. Showing the supposed male in sitû. After Lubbock.
Since a large proportion of all those helminths that require a change of hosts must needs pass into the bodies of insects, crustaceans, mollusks, or other evertebrated animals, it is evident that these lower creatures are almost as liable to be infested by parasites as the vertebrates themselves. As a rule, no doubt, the parasitic forms infesting individual evertebrated hosts are not numerous; nevertheless the water-snails form a noteworthy exception. Thus, some ten different species of parasite are found either in or upon the common Planorbis corneus; whilst Lymnæus stagnalis, Paludina vivipara, and P. impura, each support at least a dozen species. Of course, the parasites are not sexually mature, since nearly all of them are Cercariæ or larval trematodes. Snails, oysters, mussels, whelks, and other mollusks afford harbour and anchorage to a variety of parasites and messmates; but, fortunately, few or it may be none of the strictly human parasites require to pass through these intermediate bearers. Distoma crassum is possibly an exception. Save the cuttle-fishes, not many evertebrated animals are infested by sexually-mature worms. One of the most notable exceptions is that of a nematoid infesting bees. This worm was known to John Hunter, who spoke of it as “the animal that breeds in the humble bee.” In the year 1836, M. Léon Dufour first applied the term Sphærularia to this remarkable worm, which he discovered in the abdominal cavities of two species of bee (Bombus terrestris and B. hortorum). The worm was subsequently found by Von Siebold in two other species of bee (B. muscorum and B. sylvarum), but it remained for Sir John Lubbock to demonstrate that this parasite not only infests these insects, but also Bombus lucorum, B. lapidarius, B. pratorum, B. subterraneus, and Apathus vestalis. I possess specimens from Vespa vulgaris and V. rufa. Sir J. Lubbock and Mr. Cole have separately given full anatomical descriptions of the worm. According to Lubbock the so-called female is about an inch in length, of a whitish color, and 1/15″ in thickness, being bluntly pointed at either extremity. Sphærularia is everywhere covered by small warts or button-like projections, in all numbering about 800. The warts are transparent, each, according to Lubbock, projecting from 4/1000″ to 6/1000″ above the general surface of the integument. There is neither mouth, œsophagus, intestine, nor anus; but in their place a large fatty mass or corpus adiposum. Sir J. Lubbock remarks that this peculiar organ “is homologous, not with the whole intestinal canal of nematodes, but only with the intestine; and we find, in fact, that in Gordius the œsophagus is very short, and opens at once into the anterior end of the corpus adiposum; so that to pass from this genus to Sphærularia it would be necessary to shorten the œsophagus a little more, and then the wall of the corpus adiposum would be immediately attached to that of the body. So far, therefore, as concerns the corpus adiposum and the œsophagus, Sphærularia agrees neither with Gordius nor Mermis, nor, indeed, with one more than the other; since, if it agrees with Mermis albicans in the double series of large fat cells, it has no œsophagus, and in this respect more nearly resembles Gordius.” The reproductive organs consist of a single ovary, uterus, and terminally situated vulva. These organs in the full-grown females contain ova in all stages of development up to the condition of advanced yolk segmentation; but it does not appear that embryonic formation takes place whilst the eggs are still in utero. “The young animals are born soon after the eggs are laid. They are about 1/60″ in length, and 1/2500″ in diameter at the broadest part. Before Sir J. Lubbock conducted his inquiries the so-called male appears to have been overlooked. The male, if male it be, is extremely minute; that is to say, about 28,000 times smaller than the female.” Notwithstanding this very circumstantial account based on Lubbock’s determinations, Schneider has sought to show that the facts have been entirely misinterpreted. What Lubbock regards as the male worm is, in Schneider’s opinion, a female, whilst the so-called female is nothing more than a gigantic prolapsed uterus which has become many thousand times larger than the body of the worm whence it proceeded. It must be allowed that Schneider’s description and accompanying figures are very convincing. When revising the entozoa of the Hunterian Collection in 1866 I explained the specimens and dissections in accordance with Lubbock’s views. In the following year Prof. Huxley in his College Lectures supported the view of Schneider, but in his recently published manual the opinions of the Berlin helminthologist are not so much as alluded to.
Another point of special interest in connection with the parasites of insects concerns the development of Mermis albicans. At or near the time of the maturation of the ova, the parent worm, hitherto lodged within the body of some insect, buries itself in the soil. It commences its migration by boring its way out of the body of the host. Some difference of opinion exists as to the condition of the parent at the time of its wandering, for Von Siebold asserted that it quitted its parasitical mode of life “in order to become sexually mature away from the animal” infested; whereas Van Beneden states that the embryos are always formed at the time of the wandering.
From Von Siebold’s experiments it would appear that incompletely developed Mermes can become mature whilst still in the soil; but the normal condition requires the wandering to commence, as we have said, at or near the full time of embryonal development. The embryos are reproduced viviparously, and being set free, they pass a certain period of their existence in the soil. Here they grow rapidly, acquire sexual organs, and subsequently seek to “gratify their immigrative propensities,” as Von Siebold says, by selecting and penetrating the soft-bodied larvæ of lepidopterous and other insects. This entrance they accomplish by means of a sharply-pointed dentule or boring stylet, which at the time of disuse is concealed within the head. Having once gained access to the host they remain within its body until the caterpillar has become transformed into the perfect butterfly, or until their own sexual maturity is completed. Van Beneden thinks it probable that the males quit the host some time before the females, a view which, if correct, might alone account for the comparative scarcity of the males. According to Von Siebold, sexual congress occurs before the entrance of the worm into the caterpillar. This observation agrees with the generally admitted fact that hitherto no male Mermes have actually been detected in the bodies of insects. The Gordii, like Mermes, become free in damp earth and penetrate the bodies of certain insects or their larvæ. Some of them gain access to fishes. Like the free nematodes (Anguillulidæ), many of the Gordii will survive complete desiccation. The eggs of the mature worms are deposited in long agglutinated chains in water or damp situations.
I must conclude. In the body of this work will be found many notices of insect parasites that are awaiting transference to some vertebrate. I need only allude to the rôle of the mosquito, to that of the louse of the dog, and especially to that of the little myriapod (Glomeris) which, like the common glow-worm (Lampyris), possesses phosphorescent properties. I mention this again partly in correction of an entomological error (at p. [296]) which escaped me at the time of going to press. Leidy has described a mature nematode (Ascaris infecta) from Passalus cornutus, and numerous Filariæ are known to infest insects (Blatta, Forficula, Phosphuga, &c., &c.). From an earwig I obtained a filaria nearly five inches in length.
We have seen that the larvæ of Dracunculus, Cucullanus, as well as those of other important nematodes, dwell in bodies of entomostracous crustacea, whilst those of Echinorhynchus attack the Gammari and their allies. The well-known Udonella caligorum attaches itself to crustacea that are themselves parasitic.
As many of the so-called free nematodes live in the slime of animals, Villot is of opinion that no very distinct line of demarcation can fairly be drawn between the parasitic and free species. This work, however, having dealt only with genuine parasites, I have purposely omitted any detailed account of the so-called free nematoids. I mention this lest it should be supposed that I had shown a studied neglect of the more or less remarkable labours of Bütschli, Bastian, Eberth, Linstow, Marion, Villot, Claus, De Man, Carter, and many others.
Bibliography (No. 60).—Bastian, H. C., “Monograph on the Anguillulidæ, or free Nematoids, marine, land, and freshwater, with description of 100 new species,” ‘Linnean Trans.’ for 1865, vol. xxv, p. 73.—Idem (see Bibliog. No. [2]).—Idem, “Free Nematoids,” being an article in the ‘Popular Science Review’ for 1868, vol. vii, p. 163.—Brady, G. S., ‘Monograph of the free and semiparasitic Copepoda,’ London, 1878.—Bütschli, O., “Untersuchungen ueber freilebende Nematoden und die Gattung Chætonotus,” ‘Sieb. und Köll. Zeitschrift,’ 1876.—Carter, H. J., “On a Bisexual Nematoid Worm which infests the common House-fly (Musca domestica),” ‘Ann. Nat. Hist.,’ 1861, and in the ‘Bombay Med. and Phys. Soc. Trans.,’ new series, 1860.—Claparède (see Panceri).—Claus, C., ‘Beobachtungen ueber d. Organis. und Fortpflanz. v. Leptodera appendiculata,’ 1869.—Cobbold, “Note on Insect Parasites,” in ‘Rep. of Entomological Club,’ in the ‘Midland Naturalist,’ March, 1878, p. 80.—Cole, W., “Remarks on a Parasite of Humble Bees,” in ‘Journal of the Quekett Microscopical Club,’ 1875.—Dufour, L., “Sphærularia,” ‘Ann. des Sci. Nat.,’ 1836.—Dujardin, “On Mermis,” ‘Ann. des Sci. Nat.,’ 2e sér., tom. 18, p. 129.—Eberth (see Bibliog. No. [2]).—Garner, R., “Note on a Distoma,” in his paper ‘On the Lamellibranchiate Conchifera,’ ‘Trans. Zool. Soc.,’ 1841.—Ghaleb, O., “Observations and Experiments on the Migrations of Filaria rhytipleurites, a Parasite of Cockroaches and Rats,” ‘Comptes Rendus,’ July 8, 1878, and ‘Ann. Nat. Hist.,’ Aug., 1878.—Idem, “Note sur l’anat. et les migrations de deux Nématoides parasites, le Pæcilogaster blatticola et Fil. rhytipl.,” Paris, 1876 (quoted by O. von Linstow).—Giard, M. A., “On the parasitic Isopoda of the genus Entoniscus (infesting Crustacea),” from ‘Comptes Rendus,’ Aug., 1878, in ‘Ann. Nat. Hist.,’ Otc., 1878.—Idem, “On the Orthonectida, parasitic on Echinodermata and Turbellaria (Rhopalura),” ‘Ann. Nat. Hist.,’ Feb., 1878.—Grube, A., “On Cyclops as a new Cestoid-bearing Host,” from ‘Zoologisch. Anzeiger,’ Bd. i, s. 74, in ‘Journ. Royal Microsc. Soc.,’ Nov., 1878, p. 254.—Hunter, J., “Filaria of the Bee,” in ‘Catal. (by Owen) of the contents of the Mus. Royal Coll. Surg.,’ part iv, fasc. i, p. 37, 1830.—Kynston, “Worms attached to a Grasshopper,” ‘Proc. Ashm. Soc.,’ in ‘Corbyn’s India Review,’ and in ‘Journ. of Foreign Sci.,’ 1837, p. 172.—Lima, J. F. da S., “Remarks on the Filaria medinensis or Guinea-worm; on the occurrence of this parasite in the Province of Bahia; and on its entrance into the human body by drinking water;” trans. from the Portuguese by Dr J. L. Paterson, and pub. in the ‘Veterinarian’ for Feb., 1879 et seq.—Linstow, “Helminthologische Beobachtungen,” in ‘Archiv für Naturgeschichte,’ 1876.—Lubbock, Sir J., “On Sphærularia bombi,” ‘Nat. Hist. Rev.,’ 1861.—Idem, “Notes,” &c., ibid., 1864, p. 265.—Mason, J. W., “Note on the Geographical Distribution of the Temnocephala chilensis (parasitic upon a freshwater crayfish, Paranephrops setosus, in New Zealand),” ‘Annals Nat. Hist.,’ 1875, p. 336.—Marion, A. F., ‘Revision des Nématodes (&c.),’ Marseilles.—Maund, B., “A description of Filaria forficulæ,” ‘Rep. Proc. Linn. Soc.,’ in ‘Zool. Journ.,’ 1832–34, p. 263.—Meissner (see Thomson).—Owen, R. (see Hunter).—Pagenstecher (see Bibl. No. [58]).—Panceri, P. (e di E. D. Claparède), “Nota sopra une alciopide parassito dell Cydippe densa,” ‘Mem. della Soc. Ital. di Sci. Nat.,’ 1867.—Sars, “Intestinal Worm in an Acaleph.,” from ‘Wiegmann’s Archiv,’ in ‘Ann. Nat. Hist.,’ 1845.—Siebold, C. J. von, in ‘Wiegmann’s Arch.,’ 1835.—Idem, in ‘Ray Soc. Rep.’ (by Busk), 1847.—Idem, “Worms,” &c., ibid., p. 503, 1847.—Idem, “Report on Helminthology, and on the Nemertinæ” (trans. by W. B. Macdonald, in ‘Ray Soc. Rep. on Zool.,’ 1842, p. 280), Edinburgh, 1845.—Idem (see Thomson).—Thomson, A. (for review of the writings of Meissner, Von Siebold, and others, respecting the development of Mermis, Gordius, &c., see the classical and elaborate art. “Ovum”), in ‘Supp. to Todd’s Cyclop.,’ 1859.—Vogt, C., “On some Inhabitants (Cercariæ) of the Fresh-water Mussels,” from ‘Ann. des Sci. Nat.,’ in ‘Ann. Nat. Hist.,’ 1850.—Whitman, C. O., “The Embryology of Clepsine (with valuable Bibliography),” ‘Quart. Journ. Micr. Sci.,’ July, 1878.
Appendix.—The memoirs announced by Dr T. R. Lewis in the January issue of the ‘Microscopical Journal,’ and referred to at the close of my account of Filaria Bancrofti, having appeared, I fulfil the promise previously made (p. [202]). In the few lines at my disposal I may observe that the beautiful brochure (quoted below) supplies fuller details of the results already announced by Lewis in the ‘Proceedings of the Asiatic Society of Bengal.’ In respect of the nematoid hæmatozoa, the memoir is chiefly important as confirming Manson’s observations regarding the changes undergone by the Filariæ that have been transferred to the stomach of the mosquito, and especially also, as advancing some novel facts in reference to the occurrence of bird’s blood-corpuscles, associated with embryonic nematoids, in the same viscus of the insect. The worms are regarded by Lewis as transferred avian hæmatozoa, a view which gains strength by their comparison with the similar larvæ which he had detected in the blood of Indian crows (Corvus splendens). In Egypt, as Sonsino had himself informed me by letter, similar hæmatozoa are to be found in crows, and avian filariæ of this kind were long previously described, as Lewis and Sonsino point out, by Borell, Herbert, Schmidt, and Virchow. Facts of this order undoubtedly complicate matters, and suggest that extreme measure of caution in drawing conclusions, which Lewis himself everywhere displays.
Respecting the final changes undergone by the mosquito-filariæ before their re-entrance into the human body, Lewis does not appear to have gone further than Dr Manson. By rupturing the body of the most advanced larvæ, Lewis readily recognised the œsophagus and intestine, but he remarks, significantly, “I have not been able to distinguish any other differentiated viscus in any of the specimens, and certainly, nothing suggestive of differentiation of sex” (p. 83). In an earlier part of the memoir Dr Lewis takes objection to my view that the urinary nematoids found by me in a case of Bilharzia are genetically related to Filaria sanguinis hominis. His distinguished coadjutor, Dr D. Cunningham, also denies the possibility of such relationship. No doubt, if the urinary maternal worm was really oviparous my view is untenable; but the proved presence of imperfectly formed ovarian ova, in which no trace of embryonic formation was discernible, has forced upon me the conviction that prolapsus and rupture of the uterine tubes of the parent worm had occurred, and that their rupture had occasioned the escape of ova in various stages of growth. As free embryos were also detected, the adult worm was probably viviparous. There is an error in the representation of the oval-shaped ovum given in the figure (p. [183]). I retain drawings of eighteen perfect nematoid ova from the Bilharzia case, and not one of these shows any double contour of the chorional envelope. In the case of the imperfect ova, the double contour is obviously due to the close apposition of the yelk-membrane to the shell-membrane, there being no true shell. As regards “a correction” which Lewis makes in respect of the question of priority of description of the mature Filaria sanguinis hominis I can only find space to state frankly, that Lewis is perfectly correct. The error was quite unintentional on my part. The adult worm was first discovered by Bancroft, and upon the strength of his admittedly scanty record I named the worm Filaria Bancrofti. In the matter of supplying a proper diagnosis and an anatomical description I was completely anticipated by Lewis. No doubt, Dr Bancroft could have furnished a fuller description of the parasite, had he desired to do so, but here is what he says in the letter addressed to me from Melbourne on the 20th of April, 1877:—“I thought it better to send you this account of filariæ than to publish it direct, as you so kindly set me on the track of the investigation.” Here I feel constrained to remark that few, if any, of my many correspondents in helminthology, have displayed more engaging candour. Whilst actually writing this Appendix (April 15th, 1879) I have received a new record of filarious cases from Dr Bancroft, who also sends me some mosquitoes captured by a victimised patient whose blood swarmed with filariæ. In one of the captured insects Bancroft himself detected forty-five filariæ. The cases have been forwarded to the ‘Lancet’ for publication. Lastly, in reference to the closing paragraph of Bancroft’s previous letter to me (pub. in the ‘Lancet,’ Feb. 1st), I have received the following interesting commentary at the hands of Dr Silva Araujo, whose letter is dated from Bahia, March 3rd, 1879:—“Je dois vous communiquer que ce fait vient confirmer l’idée qui existe chez nous, où le peuple croit et affirme que—quand une personne qui souffrait auparavant d’erysipèle a un abcès cela la préserve de nouveaux accès. La raison ne sera-t-elle pas que dans ce cas, avec l’ouverture de l’abcès, le ver sort? Je le crois. Ces faits viennent démontrer que la cause de la maladie est le ver. Cependant nous avons ici à Bahia plusieurs confrères qui ne le croient point! Et à Rio-de-Janeiro aussi il y en a, peut-être davantage(!).” I will only add that Dr Araujo deceives himself if he imagines that the full etiological significance of parasites in relation to disease will receive general professional recognition for many years to come.
Supplement to Bibliography No. [23], p. 202 (with emendations).—Araujo, ‘Memoria sobre a Filariose ou a molestia produsida por uma nova especie de parasita cutaneo,’ Bahia, 1875.—Idem, “Da filariose,” ‘Globo,’ Jornal do Rio de Janeiro, 1876, e ‘Revista Medica do Rio de Janeiro,’ 1876, anno 3o, No. 2, 15 de Julho, p. 107.—Idem, “Caso de chyluria, elephancia do escrôto, escrôto lymphatico, craw-craw e erysipela em um mesmo individuo; descobrimento da Wuchereria filaria na lympha do escrôto. Tratamento pela electricidade com excellentes resultados,” ‘Gaz. Med. da Bahia,’ 2a serie, vol. 2o, No. 11, Nov. de 1876.—Idem, “A Filaria Wuchereri no sangue,” ‘Gaz. Med. da Bahia,’ Mar. de 1878, p. 106, e seguintes.—Idem, “A muriçoca e as filarias Wuchereri,” ‘Gaz. Med. da Bahia,’ Setembro de 1878.—Idem, “La Fil. immitis,” &c., Transl. of Mem. (l. c., Bibl., No. [45]) in ‘Lyon Médical,’ Nov., 1878, p. 319 et 363.—Bancroft, “Instance of a European having taken leprosy in Queensland,” in a letter to myself; see “Case from Bancroft,” quoted at p. 203.—Chassaniol, A. (et F. Guyot), “Hématurie graisseuse ou chyleuse,” in their “Notes de Géographie Méd. recueillies à Taïti,” in ‘Archives de Méd. Navale,’ Jan., 1878, p. 65.—Cobbold, “Worms in the Heart of Dogs,” letter in the ‘Lancet,’ April 5, 1879, p. 498.—Coles, “On Lymph-scrotum,” ‘Brit. Med. Journ.,’ March 9, 1878.—Fayrer, Sir J., “Lecture on Elephantiasis Arabum,” in the ‘Lancet,’ March 29, 1879, p. 433.—Idem, ‘Report of Pathol. Soc.,’ ‘Lancet,’ Feb. 22, 1879, p. 267.—Idem, ‘Rep. of Epidemiological Soc.,’ ibid., p. 269.—Idem, ‘Letter on Filaria;’ see Hoysted.—Ghaleb, O. (with P. Pouquier), “On Filaria hæmatica,” from ‘Comptes Rendus,’ Feb. 5, 1877, in ‘Annals Nat. Hist.,’ April, 1877.—Hoysted, J., “Notes of a Case of Filaria sanguinis in a Dog;” see Bibliog. No. [49], p. 311.—Lewis, T. R., ‘The Microscopic Organisms found in the Blood of Man and Animals, and their relation to Disease,’ Calcutta, 1879.—Idem, “The Hæmatozoa of Man (excerpt of the above),” ‘Quart. Journ. of Microsc. Sci.,’ April, p. 245 (both from ‘14th Ann. Rep. of the San. Commissioner with the Govt. of India’).—Makuna, ‘Letter respecting Fil. sang. hom. in Chyluria’ (l. c., Bibliog. No. 23).