PL A 7' YHELMINTHES. 



with the muscular movements of the host, the embryo is 

 worked into the blood-vessels of the pig, along which it is 

 carried into the muscles. Here it loses its hooks and be- 

 comes a hollow vesicle or cyst. iThe wall of the oval cyst is 

 invaginated at one side and forms a pocket. On the wall of 

 the pocket are found suckers and hooks, and it is later 

 evaginated to form the cestoid worm. Pork containing such 

 cysts is known as "measly." This is known as the cystic stage 

 or bladder-worm^ and the cysts of Tcenia solium were known 



Fig. 84. — *' Measly" Pork. 



The oval bodies are cysts. 



by the separate name of Cysiicercus cellulosce before their 

 true nature was determined. The completed bladder-worm 

 shows a large bladder, depending from which is the " body " 

 of the worm. On being introduced, still alive, into the 

 human subject the bladder, and with it the greater part of 

 the body, is lost, and the head alone survives as a creeping 

 worm, fixes itself and grows into the tapeworm. 



We may note that there is no true metage?iesis^ since the 

 fission into proglottides can hardly be regarded as a method 



