45 



THE ANIMAL PARASITES OF MAN 



secretes a brown or black cement. The spermatozoa are curved 

 rods about 2 /m long. 



Spiailes are 2 mm. long, ending in a fine point. They are moved 

 by exsertor and retractor muscles. At first they lie free in the body 

 cavity; next in a groove in the dorsal wall of the cloaca; then in an 

 isolated canal, and finally in two canals. Anteriorly each has two 

 longitudinal crests on its inner surface. These meet the correspond- 

 ing crests of the other spicule, and so form a canal along which the 

 sperm passes into the female. The gubernaculum is a thickening 

 of the dorsal wall of the cloaca. It is not a free piece, but is moved 

 by various muscles. 



FlG. 328. Ancylostoma duodenale : bursa of male. The rays 

 from left to right are: (i) anterior clef t ; (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, 

 x 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 aniericanns. 



Distribution. Africa, Egypt, Europe,, Japan, China (mainly), but in 

 association with Necator aniericanns 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. 



