52 DEVELOPMENT OF CESTODES. 



future scolex is developed at the bottom of these invaginations. 

 By a process of evagination we see that the true scolex and neck 

 are found attached to the hladder or vesicle. 



Varieties of cysts. — When only one invagination is formed, 

 the cyst is known as a (Ji/st ire reus (fig. 13, a) ; when several 

 are produced, as a Ccenunis (b) ; and when the cyst itself pro- 

 duces other cysts, and each of these secondary cysts gives rise 

 to smaller invaginations (soolices), the structure is called an 

 Erhinocon-iis (fig. 17). These structures, so formed, "may live 

 in an animal for a very considerable time ; but unless they are 





Fia. 13. — Two FORMS OF Cestode Cysts. 



A, A Cysticercncs (after Neumanu). b, A Ccenitnts. 

 s, scolices ; f, cavity of cyst. 



taken into the body of some other animal, they must eventually 

 die. Should a carnivorous or insectivorous animal, or such an 

 omnivorous one as the pig, or even man, devour in the meat 

 that they eat any of these cystic forms, the action of the gastric 

 juice, again acting upon the cestode, dissolves the walls of 

 the "bladder," and releases the rudimentary scolex or scolices 

 formed in it. These heads of future tapeworms then pass into 

 some portion of the intestine, and by means of the hooks with 

 which they are provided, and augmented by tlie suckers, they 

 anchor on to the lining mucous membrane of the small and 

 large intestines. As soon as the embryo has taken up its abode 

 on the mucous membrane the scolex commences to bud off 



