THE LIVER FLUKE : REPRODUCTION 



123 



sides of the body, and communicating by short ducts with the 

 longitudinal ducts. The Laurer-Stieda canal is a short tube 

 leading from the union of oviduct and yolk duct to a pore on the 

 back ; it is probably functionless, but in other species it serves 

 for copulation. The oviduct and yolk duct are surrounded where 



,m 



^^ 



\ ^ 7xj 7 



g 



'^^-£mt^^ 





^s.v. 



T 



Fig. 87. — The reproductive organs of a liver fluke, from the ventral side. — After 



Sommer. 



c,s., Cirrus sac ; /,, female aperture ; g., anterior lobes of gut ; m., mouth ; ov., ovary (dark) ; p., penis; 

 S.V., seminal vesicle ; sh.g., shell gland ; T., testes (anterior) ; ut., uterus ; v.d., vas deferens ; y.gl. 

 diffuse yolk glands. 



they join by a rounded mass, which is known as the shell gland 

 though it does not form the egg shell, which is secreted by the 

 yolk glands, which are numerous, minute, and unicellular. 

 The shell glands may harden the shell, or their secretion may 

 activate the sperms. From this point the joined ducts proceed 

 forwards as a wide, twisted tube, the uterus, to the generative 



