38 



THE LIVER-FLUKE. 



this country is Limrusus inmcatulus (fig. 140, a). On arriving 

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

 hecomes 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 Ralid! (em). Each redia is about J^th of an inch in 



FlO. 8.— LlFE-HISTOBV 01' DiSTOMUM HEPATICra. 



A, Ciliated embiyo. b, Sporocyst. c, Reiliffi. n, Ceroaria. 



c, Pigment spots; }A, pliarynx ; })A(i), l)liiul-gut; c, cercarise; m, germinal cells; 

 ■•m, young redia; rf, lateral "fins"; ii{i), anterior siicl;er of cercoria ; a<ii), ventral 

 sucker ; a', cesophagus ; dt, 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 (c) stOl 

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

 They, unlike the sporocyst, are provided with an alimentary 

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

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

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

 twenty cercariee are produced from oaeli redia. These little 



