Drepanidotænia.—Body, broad lanceolate, testes three, female genitalia antiporal beside the testes. Scolex small, with eight hooks. Neck very short, longitudinal muscle bundles very numerous. No accessory sac opening into genital atrium.
Hymenolepis.—Narrow, female genitalia ventral to or between testes.
[283] Proc. Zool. Soc., 1911, p. 9.
[284] A third cysticercoid resembling this, but without hooks, has also been found.
[285] [The larval stage of the Davaineas occurs in slugs (Limax) and snails (Helix).—F. V. T.]
[286] The Greeks termed the tapeworms ἕλμινθες πλατεῖαι, more rarely χηρία (= fascia); the Romans called them tænia, tinea, tæniola, later lumbrici, usually with the addition lati, to distinguish them from the Lumbrici teretes (Ascaridæ). The proglottids were called Vermes cucurbitini; the cysticerci χάλαζαι (hailstones), later hydatids. Plater (1602) was the first to differentiate Tænia intestinorum (= Bothriocephalus latus) amongst the Lumbrici lati of man from Tænia longissima (= Tænia solium). The term solium was already used by Arnoldus Villanovanus, who lived about 1300; and, according to him, it signifies “cingulum” (belt, chain), while N. Andry, in 1700, traces this word from “solus,” because the worm occurs always singly in man. Leuckart and Krehl derive the word “solium” from the Syrian “schuschl” (the chain), which in Arabian has become “susl” or “sosl,” and in Latin has become “sol-ium.” What Linnæus described under the term Tænia solium was really Tænia saginata; the latter was first distinguished by Goeze, but was forgotten until Küchenmeister, in 1852, again called attention to the differences.
[287] The larvæ which on rare occasions are found in the muscular system of sheep are either strayed specimens of Cysticercus tenuicollis, which normally develop in organs of the abdominal cavity, and appertain to Tænia marginata of the dog, or actually Cysticercus cellulosæ. (Cf. Bongert, in Zeitschr. f. Fleisch- u. Milchhyg., 1899, ix, p. 86.)
[288] According to Gerlach only young pigs (up to 6 months old) are capable of infection, and perhaps the failure may have been due to the animals chosen for experiment being of the wrong age.
[289] Dressel, for instance, examined eighty-seven persons suffering from cysticercus, and found it seventy-two times in the brain, thirteen times in the muscles; K. Müller, in thirty-six cases, found it twenty-one times in the brain, twelve times in the muscles, three times in the heart; Haugg, in twenty-five cases, found it thirteen times in the brain, six times in the muscles, twice in the skin, etc. According to Graefe, amongst 1,000 ophthalmic cases in Halle and Berlin, there was one with cysticercus in the eye; in Stuttgart there was only one in 4,000, in Paris one in 6,000, and in Copenhagen one in 8,000.
[290] The diagnosis as a rule is not difficult; the patients themselves frequently observe the pumpkin seed-like segments in the fæces. But in such cases the diagnosis must still be confirmed. In other cases the discovery of the oncospheres in their embryonal shells (embryophores), which cannot be confounded with the other constituents of the fæces, gives complete certainty, although the differential diagnosis between T. solium and T. saginata is hardly possible from the embryophores; but, if evacuated segments are placed between two slides and lightly pressed, the species is easily recognizable by the shape of the uterus (cf. figs. [239] and 241).