252 PLATHELMIXTHES 



hooks. These parts are at tlrst inverted and only come to their definitive 

 position on xhe outside of tire scolex -when the hitter is protruded as one 

 v-ould turn out the imger of a glove. Rarely is tlie scolex protruded at 

 tliis time (cysticercus of the mouse liver) and begins the formation of 

 proglottids. Even in this case they do not become sexually mature until 

 in the intestine of the cat. 



The furtlier development follows when the cysticercus is taken into the 

 stomach of the new host ^\^■^en man, for instance, eats infected ('measly') 



Fig. 230. — Structure and development of the c\'sticerus (C. cellulosa^ of Tirnia 

 solium), a, measly meat, natural size; below an escaped cysticercus; b, cysticercus, 

 with e.xserted scolex, enlarged; c-c. development of the scolex, more enlarged; c, young 

 cysticercus with blastema of scolex (above) and water-vascular net; </, c, dil^'crent stages 

 of scolex in receptaculum, the cysticercal wall mostly remo\'ed. 



pork, the cysticerci are freed by action of the digestive juices and the scolex 

 is everted. The embryo passes to the intestine, becomes attached and, 

 surrounded by nourishment, begins to grow, the bladder remaining at- 

 tached to the hinder end. Soon the formation of proglottids begins in the 

 piece conirecting the bladder with the scolex So rapid is the growth that 

 in ten or twelve weeks Tccuta soliuin begins to set proglottids free. 



In cases where the bladder reaches a considerable size it may produce more 

 than a single scolex. The bladder of Ca-nunis ccnhralis, which lives in the 

 brain of sheep, produces hundreds of scolices. The number is even greater in 

 Tail id ccliiiiococcus, in which the bladder increases by budding, and by the 



