Fig. 234.—Scolex of Davainea madagascariensis. The hooks have fallen off. 14/1. (After Blanchard.)
Davainea madagascariensis, Davaine, 1869.
Syn.: Tænia madagascariensis, Dav.; Tænia demerariensis, Daniels, 1895.
This worm measures 25 to 30 cm. in length; the head has four large round suckers; the rostellum has ninety hooks (18 µ in length); there are 500 to 700 segments, of which the last 100 are filled with eggs and form half of the entire worm. The segments, when mature, measure 2 mm. in length by 1·4 mm. in breadth; genital pores unilateral; about fifty testes; the uterus consists of a number of loops, which at each side are rolled up into an almost spherical ball; when filled with eggs the convolutions unwind, permeate the segment and then lose their wall; the eggs lying free in the parenchyma become finally surrounded, one, or several together, by proliferating parenchymatous cells; this is how the 300 to 400 egg masses, taking up the entire mature segment, are formed. The globular oncosphere (8 µ) is surrounded by two perfectly transparent shells, the outer of which terminates in two pointed processes.
Davainea madagascariensis has hitherto been found in man only (eight times). Davaine described this species from fragments sent to him from Mayotta (Comoro Islands), which were found in two Creole children. Chevreau observed four cases in Port Louis (Mauritius), likewise in children; Leuckart received the first perfect specimen—it was obtained from a three year old boy, the son of a Danish captain, in Bangkok; Daniels, at the post-mortem of an adult native of George Town, Guiana, found two specimens (Tænia demerariensis); and finally Blanchard describes another perfect specimen which was in Davaine’s collection of helminthes in Paris, and which was obtained from a little girl 3 years old, of Nossi-Bé (Madagascar). The intermediate host is unknown.
Davainea (?) asiatica, v. Linst., 1901.
Syn.: Tænia asiatica, v. Linstow.
There exists only one headless specimen of this species, which is not quite adult, and which is preserved in the Zoological Museum of the Imperial Academy of Science in Petrograd. It came from a human being and was found by Anger in Aschabad (Asiatic Russia, near the northern frontier of Persia). The specimen measures 298 mm. in length. The breadth anteriorly is only 0·16 mm., the posterior part measures 1·78 mm. across. The number of segments is about 750. The genital pores are unilateral; the testes are globular and lie in a dorsal and ventral layer in the medullary layer; the cirrus pouch is pyriform, 0·079 mm. in length and 0·049 mm. in breadth; the female glands lie in the fore-part of the segments, the ovary reaching to the excretory vessels; the vitellarium is small and round. The vagina has a large fusiform receptaculum seminis; the uterus breaks up into sixty to seventy large, irregularly polyhedric eggsacs.