Fig. 328.—Ancylostoma duodenale: bursa of male. The rays from left to right are: (1) anterior cleft; (2) antero-external; (3) and (4) median doubled, i.e., antero-median and postero-median; (5) postero-external arising from a common trunk with the posterior. × c. 120. (After Looss.)
Genital Cone is a prominence on the floor of the bursa on the ventral side of the body, on which the genito-anal orifice opens. The cone is only slightly marked in Ancylostoma duodenale, but is much more prominent in Necator americanus.
Distribution.—Africa, Egypt, Europe, Japan, China (mainly), but in association with Necator americanus in Southern States of America, British India, Assam, Burma, Hongkong, Liberia, Jamaica, Martinique, Costa Rica, Colombia, Antigua, Guadeloupe.
Habitat.—The worms live in the jejunum, less frequently in the duodenum, of man only.
Food.—The worms feed on the mucous membrane of the gut, attaching themselves to the base of the villi, sucking these in; and when these are destroyed they attack further the submucosa. As a rule the worms have no blood in the gut, but in their attack on the submucosa a blood-vessel may be eroded, and so the gut of the worm filled with blood.
Development.—The eggs are oval with broadly rounded poles, 56 µ to 61 µ by 34 µ to 38 µ. In fresh fæces they contain four granular nucleated segmentation masses of the ovum (fig. 329) separated by a clear space from the shell.