THE ANIMAL PARASITES OF MAN 



the oral sucker. Both suckers are larger than the corresponding ones 

 in S. hcematobium. Body usually smooth, but in the fresh state 

 numerous fairly evident spines along the margin of the canal. (Eso- 

 phagus : two bulbs. The junction of the gut forks more posterior than 



in S. hceniatobium, the median united gut 

 stem occupying a quarter to one-fifth to 

 one-sixth of the body length. An excre- 

 tory canal runs along each side of the 

 body, opening into the dorsal excretory 

 pore. Testes irregularly elliptical, six to 

 eight in number, in the anterior part of 

 hind-body. The vasa efferentia unite 

 into a common vas deferens which opens 

 directly behind the ventral sucker. The 

 seminal vesicle lies just behind this. 



Female. Up to 26 mm., generally 

 thinner than the male. Surface smooth. 

 Suckers armed with fine spines. Ventral 

 sucker larger than oral. Body thicker 

 behind the region of the ovary. The 

 gut forks unite immediately behind the 

 ovary. The united gut much thicker 

 than in S. hcematobium. Ovary elliptical, 

 almost in the mid-body, its hinder por- 

 tion dilated. The oviduct arises from 

 its posterior end and then runs sinuously 

 forward, where it is joined by the vitel- 

 larian duct ; the vitellarium well deve- 

 loped, extending from behind the ovary 

 almost but not quite to the posterior 

 end as in S. hcematobium. Shell gland 

 ducts enter at the junction point of 

 oviduct and vitelline duct. The canal 

 here forms an ootype and then proceeds 

 as the uterus to open directly behind 

 the ventral sucker. The uterus occupies 

 almost half the hind-body. In S. hcema- 

 tobium this is not so. The uterine canal 

 is cleft-like, i.e., its dorso-ventral diameter 

 is much greater than its lateral diameter. 

 The number of eggs varies from about 

 50 to 300 from observations made in various hosts. 



Eggs. In utero assume various shapes, as they are soft ; the lumen 

 of the uterus is narrow. Outside they are oval, faint yellow, double 



FIG. 176. Schistosoma japoni- 

 cum : anterior end with testes ; 

 posterior end with point of union 

 of caeca. Length of worm about 

 10 mm. (After Katsurada.) 



