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Zoological distribution.—The adult form inhabits pythons and other snakes. It has been found in Python sebæ by Wyman, Sambon, and others; in the royal python (Python regius) and in the nose-horned viper (Bitis nasicornis) by Sambon. The larval—or, more correctly, the nymphal—form has been found in the lion, in the leopard, in the mandrill, in the aard-wolf. Pruner found it in the giraffe, Looss in Syke's monkey (Cercopithecus albigularis), and Sambon in the Pousargues guenon (Cercopithecus pousarguei) and in the African hedgehog (Erinaceus æthiopicus).

The parasite (Fig. 166).—Body vermiform, yellowish translucent, larger in females (9-12 cm. long by 5-9 mm. broad) than in males (3-4·5 cm. long by 3-4 mm. broad); cylindrical in the anterior half, slightly tapering posteriorly, and terminating in a blunt-pointed cone. It is characterized by the presence of prominent opaque rings 1-2 mm. wide, numbering 16 or 17 in the males, 18 to 22 in the females, placed somewhat obliquely and separated by interannular spaces 2-5 mm. wide except between the first rings, which are faintly indicated by shallow linear furrows. There is no clear distinction between cephalothorax and abdomen, and the rings nearest the cephalothorax are sometimes so indistinct that it is almost impossible to make out their actual number. The cephalothorax is depressed, slightly convex on the dorsal surface, more or less concave on the ventral surface. It is rounded anteriorly; posteriorly it is limited by the first body rings. It varies considerably in length; its breadth is from 4 to 7 mm. The mouth, opening on its ventral surface about 1 mm. from the anterior border, is lipped by a chitinous ring. Above it are two prominent papillæ. On either side of the mouth are two protractile chitinous hooks similar in shape to feline claws. The anus is terminal at the posterior end. The genital orifice of the male is at the anterior end of the abdomen in the middle of the ventral surface of the first body ring; that of the female opens in the middle of the ventral surface of the caudal cone at about 1 mm. from the anus. The female is oviparous; the eggs are broadly elliptical.

The nymphal form (Fig. 167) is usually found spirally coiled within a cyst, the ventral surface corresponding, as a rule, to the convexity of the curve. In shape and structure the nymph closely resembles the adult, and the number of rings is the same. Calcification of the nymphal form in the liver may take place.