38 



THE LIVEK-FLUKE. 



this country is Limncms truncatulus (fig. 140, a). On arriving 

 at the respiratory cavity of this snail the embryo encysts, and 

 becomes converted into a body known as the sporocyst (fig. 8, b). 

 The sporocyst is an oval body with neither mouth nor anus. 

 Its contents split up into a number of bodies, usually varying 

 from six to eight. These structures, found inside the sporocyst, 

 have been formed asexually by internal gemmation, and are 

 known as Eedias (em). Each redia is about ^^^th of an inch in 



Fig. 8. — Life-histoey of Distomum hepaticum. 



A, Ciliated embryo, b, Sporocyst. c, Bedise. d, Cercaria. 



e, Pigment spots ; ph, pharynx ; p?t(i), blind-gut ; c, cercariffi ; m, germinal cells ; 

 ?m, young redia; r/, lateral "fins": a(i), anterior sucker of cercaria ; a(iiX ventral 

 sucker ; ce, oesophagus ; di, blind-gut, (After Leuckart and Thomas.) 



length. Later the sporocyst bursts and the redise are released, 

 passing out of the rupture one by one. The redise (o) still 

 remain in the snail, where they move about in the mantle cavity. 

 They, unlike the sporocyst, are provided with an alimentary 

 canal and mouth (joh). Again asexual reproduction comes into 

 play, for each redia gives rise by budding (internal) to a number 

 of tailed creatures, known as Gercarice (c). About fifteen to 

 twenty cercariee are produced from each redia. These little 



