TREMATODA 



137 



is connected with the vessels. In such cases there are also ciliary 

 lobes in the tubules. 



The contents of the entire apparatus usually consist of a clear 

 or sometimes reddish fluid ; in some species there are larger or 

 smaller granules, and occasionally concretions also occur. 



Sexual Organs. Nearly all the Trematodes are hermaphrodites, 

 and only a few (Schistosominea, Koellikeria) are sexually differen- 



y.d. 



FIG. 72. Opisthioglyphe endo- 

 loba (Duj.), from the frog. Male 

 genitals. 71/1. A.s., abdom- 

 inal sucker; C.p., cirrus pouch, 

 with cirrus, prostatatic cells 

 and vesicula seminalis ; G.p., 

 genital pore ; T., testes ; Ut., 

 terminal portion of the uterus ; 

 V.d., vas deferens. (After 

 Looss.) 



V.S.: 



FIG. 73. Opisthioglypbe endoloba (Duj.). Female 

 genitals. 71/1. A., Abdominal sucker ; C., pouch 

 of cirrus ; V.d. , vitelline duct ; V.s., vitelline sac ; 

 L.C., Laurer's canal ; 7?.s., receptaculum seminis ; 

 U., uterus ; K., ovary. (After Looss.) 



tiated. The sexual organs usually lie in the " central field " 

 surrounded by the intestinal branches ; the vitelline sacs, on the 

 other hand, are, as a rule, placed laterally beyond the intestinal 

 branches in the lateral areas. 



The male apparatus 1 is composed of two variously formed 

 testes (fig. 72) (globular, oval, indented, lobulated, or ramified) 

 which may lie side by side or one behind the other, from 

 each testicle a tube (vas efferens) originates ; sooner or later, both 

 tubes become as a rule united to form the muscular vas deferens 



1 The following description mostly relates to the Fasciolidea. 



