“(n).—The yelk-molecules surrounding the germinal vesicle are not directly transformed into an embryo.”
Fig. 76.—Echinorhynchus anthuris. 1, Attached to the intestine; 2, specimen enlarged; 3, ovarian vesicle, including germs; 4, germs in various stages; 5, vesicle with germs more advanced; 6, 7, eggs in their capsules; 8, free egg. Original.
As regards the acanthocephalous parasites of reptiles, I may observe that Echinorhynchus anthuris is very common in the lesser water newt (Lissotriton punctatus). In the accompanying illustration (Fig. 76) I have represented the free ovarian egg-bearing bodies, the development of the ovum, and the adult worms. For anatomical details, however, I must refer to my earlier treatise (‘Entozoa,’ p. 100 et seq.).
Amongst the species of entozoa that were found by me at the Zoological Society’s Menagerie I may mention Distoma coronarium and Ascaris lineata, from the intestines of Alligator mississippiensis; Dist. Boscii, from an American snake (Coluber); an immature nematode, from the heart of Coluber Blumenbachii; and Echinorhynchus inflexus, attached to the intestines of a snapping turtle (Chelydra serpentina). I may add that the lungs of the alligator also contained examples of Diesing’s Pentastoma oxycephalum. An Egyptian hooded snake (Naia haje), which died at the Zoological Gardens in 1859, furnished a new species of pentastome (P. multicinctum). Dr George Harley described and anatomised this worm with remarkable care. To Harley’s memoir Prof. Leuckart did ample justice in his work on the ‘Pentastoma.’ Several new species of reptilian entozoa have recently been described by Dr von Linstow; and Dr Solger has found a new trichosome (T. recurvum) beneath the skin of a young crocodile (probably Croc. acutus). For further particulars I refer to the revised descriptions and additions by Diesing, Molin, Schneider, and other systematists.
Bibliography (No. 58).—Baird, W., “Description of a new Entozoon from the Diamond Snake,” in ‘Proceed. Zool. Soc.’ for 1865, p. 58, and in ‘Ann. Nat. Hist.’ for July, 1865, p. 52.—Blanchard, “On Polystoma,” ‘Ann. des Sci. Nat.,’ 3e ser., viii, p. 331.—Canton, E., “An account of some Parasites attached to the Conjunctivæ of the Turtle’s Eyes,” ‘Quart. Journ. Micr. Sci.,’ and ‘Dublin Med. Press,’ 1861 (with remarks by myself).—Cobbold, ‘Notes,’ &c. (l. c., Bibl. No. [57]), and in ‘Linn. Trans.,’ 1857.—Crisp, E., “Note on Cysticerci and Trichocephali from an Alligator,” ‘Path. Soc. Trans.,’ 1854.—Diesing, ‘Revision der Cercarieen,’ 1858; ‘Revis. der Myzelminthen,’ 1858; ‘Nachträge (u. s. w.),’ 1859; ‘Revis. der Nematoden,’ 1860; ‘Revis. d. Turbellarien,’ 1861; ‘Revis. d. Cephalocotyleen,’ 1863.—Idem, ‘Monographie d. Gatt. Amphistoma und Diplodiscus,’ and ‘Nachträge zur Monog. der Amph.,’ 1839.—Dujardin, ‘Hist. d. Helm.’ (l. c., pp. 320, 526, &c.).—Eberth, “On Myoryktes Weismanni from the Muscles of the Frog,” trans. by Busk, from ‘Siebold und Kölliker’s Zeitschrift,’ in ‘Lond. Micr. Journ.,’ Jan., 1864.—Gastaldi, ‘Cenni sopra alcuni nuovi Elmint.,’ Torino, 1854 (new flukes from frogs and salamanders).—Glüge, “On Entozoa in the Vessels of Frogs,” from ‘Comptes Rendus,’ in ‘Micr. Journ. and Struct. Rec.,’ p. 207, 1842; see Grübe and Valentin.—Grübe, “On the Entozoa of the Frog, and on the Pathology of that Batrachian,” from ‘Comptes Rendus,’ in ‘Micr. Journ. and Struct. Rec.,’ p. 246, for 1842; see also Mandl.—Harley, G., “On the Anatomy of a new Species of Pentastoma found in the Lung and Air-sac of an Egyptian Cobra,” ‘Proc. Zool. Soc.,’ June, part xxv, p. 115, 1857.—Leuckart, ‘Bau und Entwickelungsgeschichte der Pentastomen,’ Leipsig, 1860.—Linstow, ‘Enthelminth.’ (l. c., Bibl. No. [57]).—Macalister, A., “On the presence of certain Secreting Organs in Nematoidea,” ‘Ann. and Mag. of Nat. Hist.’ for 1865.—Idem, “On the Anatomy of Ascaris dactyluris,” ‘Proc. Nat. Hist. Soc. of Dublin,’ vol. iv, 1865.—Mandl, “Development of Entozoa (Ascaris nigrovenosa of the frog),” from ‘Rep. of French Acad. of Sci.,’ in ‘Month. Journ. of Med. Sci.,’ vol. ii, p. 1081, 1842.—Molin, ‘Monog. del gen. Myzelminth; Mon. del gen. Physaloptera; Mon. del gen. Histiocephalus; Mon. del gen. Spiroptera;’ Wien, 1859–60.—Pagenstecher, ‘Trematodenlarven und Trematoden,’ Heidelberg, 1857.—Sibbald, J., “On the Nematoideum natricis,” ‘Path. Soc. Trans.,’ vol. viii, 1857.—Solger, “Ueber eine neue species von Trichosoma,” ‘Arch. f. Naturg.,’ 1877.—Valentin, “On Parasites in the Bladder of the Frog” (from ‘Repertorium’), in ‘Micr. Journ. and Struct. Record,’ 1842, p. 183.—Vogt, C., “On Filaria in the Vessels of the Frog,” from ‘Müller’s Archiv,’ in ‘Micr. Journ. and Struct. Rec.,’ p. 241, 1842.—Wedl, F., “Beiträge zur Lehre von den Hæmatozoen,” ‘Sitzungsb. Akad.,’ Wien, 1850 (from the blood of frogs, &c.).—Zeller, E., “Weiterer Beitrag zur Kentniss der Polystomen,” ‘Sieb. und Köll. Zeitschrift,’ 1875.
Part III (Pisces).
Swarms of entozoa infest fishes, and it is hard to say whether they are less numerous in the inhabitants of fresh water than in those of salt water. More attention has been paid to the helminths of the fishes than to the internal parasites of birds and reptiles, consequently, the number of known species must be estimated by many hundreds. In like manner a great deal has been written respecting the ectozoa of fishes. These parasites, often called fish-lice, belong chiefly to the haustellated crustaceans, and are better known by the title of Epizoa. No account of them can be afforded in this treatise, but some trifling notice of the literature of the subject will be given below.
About a hundred distinct species of fluke have been described as infesting fishes. Not many of these worms possess more than a zoological interest; nevertheless, from that point of view certain types are very curious. Most of the species dwell in the stomach and intestines, but, as more or less remarkable exceptions, I may mention Distoma seriale infesting the kidney of Salmo umbla, D. longum (Leidy) from the pharynx of Esox estor, D. polymorphum from the urinary bladder of the common pike (Esox lucius), D. obesum from the gall bladder of Salminius and other Brazilian fishes (Xiphostoma, Leporinus), D. tornatum attached to the gills of Coryphæna hippuris, D. rosaceum attached to the palate of Lota communis, and D. contortum attached to the gills of Orthagoriscus mola. Most of the forms found encysted are sexually-immature worms. To these belong D. annuligerum, found by Nordmann in cysts in the vitreous humour of the eye of the perch (Perca fluviatilis), and D. embryo from the liver and peritoneum of Acerina vulgaris. One of the largest and most remarkable of the flukes inhabiting marine fishes is the Distoma clavatum, found by Tilesius in the stomach of Pelamys, by Pohl in Thynnus, and by Bosc in Coryphæna. In the last-named fish it has been found adhering to the gills, in the liver, and in the intestines. In August, 1865, I obtained this parasite from a sword-fish (Xiphias gladius), and in the same piscine host I also found examples of four other species of helminths (Tetrarhynchus attenuatus, scolex of another tetrarhynch, Bothriocephalus plicatus, Ascaris incurva). Believing Distoma clavatum to represent several forms hitherto regarded as distinct, I append a few particulars respecting it. Five examples of this worm were obtained by me from the stomach of a sword-fish. Generally they varied in length from four lines to two inches. They differed somewhat in shape, but all had the so-called head and neck directed backwards. Below the ventral sucker the two largest specimens were distended with eggs and black pigment. All of them likewise exhibited more or less well-marked transverse rugæ, the last ring surrounding an orifice which represented the outlet of a large contractile vesicle. The eggs averaged 1/800″ in length.
When revising the entozoa of the Museum of the Royal College of Surgeons I encountered many parasites without labels attached. Amongst these were several flukes, which, though differing from each other in size and shape, appeared to be identical. One of these specimens turned out to be the particular Distoma clavatum described and figured by Professor Owen in the ‘Zoological Society’s Transactions.’ Several of the others I made out to be part of a series contributed by Mr George Bennett, who also gave specimens to the British Museum, but the College Museum stores contained yet a third group of specimens of uncertain history. The large fluke described by Prof. Owen was formerly in the collection of the Rev. Lansdown Guilding. In Dr Baird’s catalogue the specimens presented by Mr Bennett are stated to have come from the stomach of a bonito, and probably Mr Guilding’s specimens may be referred to the same “host.” Be that as it may, the specimens differ from each other in a very striking manner. In the year 1730 M. Garsin first described this worm under the generic title of Hirudinella. He says:—“Cet insecte tiré de l’estomac de la Bonita ne vécut qu’environ deux heures. Exposé à l’air il étoit languissant, et reprenoit de la vivacité dans de l’eau de mer. Il diminua sensiblement de volume pendant qu’il vivoit encore.” M. Garsin’s description is accompanied by three figures. His specimens do not appear to have exceeded 11/2″ in length. In 1774 Pallas described a trematode (Fasciola ventricosa). It measured two inches in length. All that he says regarding its source is as follows:—“Ex Amboyna missum fuit singulare hoc molluscum, quod ad aliud quam Fasciolarum genus referre non potui, in quo quasi gigas erit.” He remarks upon its pale white color, and notices particularly the soft elastic body proper, which when wounded gave out a dark matter resembling soot. This material, when examined with the microscope, appeared fresh; it was not the result of decomposition. Pallas also gives many other details, accompanied by a figure. In 1790 Menzies likewise described and figured a fluke about two inches long. He calls it Fasciola clavata:—“It is of whitish color, somewhat pellucid, discharging at its mouth a black-colored fluid, which can easily be perceived through its body. I have often found it,” he adds, “in the maws of the bonito, between the tropics in the Pacific Ocean.” Notwithstanding the similarity of description, Menzies does not appear to have recognised the identity of his worm with that described by Pallas. Prof. Owen, however, subsequently established this identity, and referred to this species as the Fasciola clavata seu ventricosa. On the other hand, the British Museum Catalogue represents Pallas’s worm as specifically distinct from that of Menzies, but as identical with the specimen described by Prof. Owen from Mr Guilding’s collection.