Fig. 28.—Head of Bothriocephalus cristatus, viewed from the front. After Davaine.
Bothriocephalus cordatus, Leuckart.—This species is identical with a worm long ago described by Pallas and Linneus. At present it is only known to infest the residents of North Greenland, but it is probably distributed throughout the north generally. It attains the length of about one foot, and has a small heart-shaped head, whose apex is directed forwards. The neck is so obscure that it may be said to be altogether wanting, the segmentation of the body being well marked immediately below the head. Though so small a species, Leuckart, who first described it, counted between six and seven hundred joints. As in the broad tapeworm, the reproductive orifices are serially disposed along the centre of the ventral line, but a close inspection shows that the folds of the egg-bearing organ are comparatively more numerous. This worm does not appear to be a frequent resident in the human body, though it is by no means uncommon in the dog. Possibly it may yet be found in the inhabitants of some of our northern and western isles.
Bothriocephalus cristatus, Davaine.—This cestode measures between nine and ten feet in length, and is characterised by the presence of two remarkable prominences, together forming a sort of rostellum or crest which is covered by numerous minute papillæ. The full-grown segments are less than half an inch in breadth; the body of the parasite being narrower than that of the broad species. The original description of the parasite by Davaine is based on two specimens, one of which, quite perfect, was obtained from a child five years old, under Dr Féréol’s care at Paris. The other was passed spontaneously by an adult residing at Haute-Saône. I have here copied one of Davaine’s original figures of the head of the worm.
Bibliography (No. 19).—Bertolus, “Mém. sur le development du Dibothrium latum” (in Appendix to Duchamp’s work, see Bibliog. No. 59).—Blanchard, “Recherches, &c.,” ‘Ann. des Sci. Nat.,’ ser. 3, Zool., Pl. 11, 12, 1848.—Böttcher, “Studien ueber den Bau des Both. latus,” ‘Virchow’s Archiv,’ s. 97 et seq, 1864.—Bremser, l. c., Bibl. No. 1, s. 88, 1824.—Chiaje, ‘Compendio, &c.,’ Tab. iii, figs. 1–5, 1833.—Cobbold, ‘Entoz.,’ p. 289, 1864.—Idem, “Remarks on the Broad Tapeworm” (with a letter from Dr Fock), the ‘Veterinarian,’ July, 1878.—Creplin, in Ersch and Gruber’s ‘Encyclop.,’ 1839, p. 296.—Davaine, ‘Traité,’ l. c., 1860; 2nd edit. (passim), 1877.—Idem, art. ‘Les Cestoïdes,’ l. c., Bibl. No. 2, p. 580–591, 1876.—Dujardin, l. c., Bibl. No. 1, p. 612, 1845.—Eschricht, D. F., ‘Anat-physiol. Untersuchungen ueber die Bothriocephalen,’ Breslau, 1840.—Fock (see Cobbold).—Heller, ‘Darmschmarotzer,’ l. c., s. 606, 1876.—Knoch, ‘Petersburger Med. Zeitschrift,’ 1861.—Idem, ‘Die Naturgeschichte des breiten Bandwurms (B. latus, auct.),’ St Petersburg, 1862.—Küchenmeister, ‘Ueber cestoden,’ l. c., 1853.—Leuckart, ‘Die Blasen Bandwürmer,’ 1856.—Idem, ‘Die mensch. Par.,’ Bd. i, s. 414–448, und 757, 1863; and Bd. ii, s. 866, 1876.—Owen, Todd’s ‘Cyclop.,’ 1837.—Sömmer und Landois, aus Sieb. und Köll. Zeitschr., ‘Beiträge zur Anatomie der Plattwürmer,’ Leipsig, 1872; see also the résumé in ‘Nature’ for Aug., 1872, p. 278.—Wawruch, ‘Pract. Monograph. d. Bandwürm-Krankheit,’ 1844, s. 33.
Fig. 29.—Tænia echinococcus Strobile. Mag. 30 diam. Original.
Echinococcus hominis (the common hydatid).—This larval entozoon has acquired various names according to the kind of bearer in which it happens to have been found; but all the true hydatids or acephalocysts, whether infesting man or animals, are referable to one and the same species of parasite. They have been termed Echinococcus hominis, E. veterinorum, E. polymorphus, E. exogena, E. endogena, E. multilocularis, according to circumstances. All of them represent a juvenile stage of the Tænia echinococcus or hydatid-forming tapeworm which infests the dog and wolf. Experimental proof of this fact has been furnished by Von Siebold (1852), Haubner, Leuckart, Küchenmeister, Van Beneden, Naunyn, Nettleship, Krabbe, and others.
The first successful rearing of Tæniæ with human hydatids was accomplished by Naunyn (1864), his results being subsequently verified by Krabbe and Finsen (1865). Zenker, Ercolani, and several others, including myself, also conducted feeding experiments with human hydatids which were attended with negative results. In the case of one of my experimental dogs the animal was liberated by an ill-disposed person before I had opportunity to destroy it. As the experiment was carefully conducted, the animal may have proved a source of fresh echinococcus-infection. Mr E. Nettleship’s eminently successful experiment was made with hydatids obtained from a sheep. The converse experiment, namely, that of rearing hydatids with the mature proglottides of Tænia echinococcus administered to animals, has been performed most successfully by Leuckart, and by Krabbe and Finsen; by the former in the pig, by the latter in a lamb, with tapeworms that had also been reared by experiment. Zenker, later on, reared the Tænia from hydatids obtained from an ox.