236 



ZOOLOGY 



SECT. 



vil 



cloaca. At the base of the penis, where the vasa deferentia meet, 

 the median canal is slightly enlarged to form a rounded dilatation, 



the vesicula seminalis. Into the 

 median canal open the narrow ducts 

 of a number of unicellular glands, 

 the prostate glands (pr.). 



The female part of the reproduc- 

 tive apparatus consists of ovaries 

 (germaria), oviducts, vitelline glands, 

 uterus, and muscular sac. The ger- 

 maria (ov.) are two in number 

 small rounded bodies situated near 

 the anterior end, each connected 

 with an elongated duct, the oviduct. 

 The two oviducts (od.) unite pos- 

 teriorly to form a short median 

 common oviduct opening into the 

 genital atrinm. With this cavity are 

 connected also the uterus (ut.), a 

 median rounded chamber, and a 

 thick- walled muscular body, the 

 muscular sac (m.). Numerous branch- 

 ing tubes the vitelline glands (vit.) 

 open into the oviducts. 



Reproduction is entirely sexual. 

 The oosperm is enclosed within a 

 protecting case or shell, which con- 

 tains also a quantity of food-yolk 

 derived from the vitelline glands. 

 When the larva has reached a cer- 

 tain stage it develops a temporary 

 larval mouth and gullet (see Fig. 

 222), and swallows the food-yolk, 

 by the aid of which it grows 

 rapidly. The larval mouth dis- 

 appears, and a new one the per- 

 manent mouth is developed in its 

 place. When the embryo leaves the 

 shell, it has assumed the character- 

 istic shape of the parent. 



ii. The Liver-Fluke (Fasciola 

 hepatica). 



General Features. The Liver- 

 Fluke of the Sheep, which is to 

 be found in the interior of the larger bile-ducts of the infested 

 animal, is a soft-bodied worm of flattened leaf-like shape 



vit 



FIG. 187. Flanaria. Reproductive 

 system, m. muscular sac ; ov. 

 germarium ; p. penis ; ph. pharynx ; 

 pr. prostate ; tes. testes ; ut. uterus ; 

 v . d. vas deferens : vit. vitelline 

 glands. (After Jijima and Hat- 

 schek.) 



