PLATYHELMIA. 45 



being the cyst is dissolved, the scolex is everted (Fig. 13), and 

 the proscolex digested. The scolex then passes on into the in- 



Fig. 12. TAPEWORM (from Landois and Stirling).- Cysticerci of Tsenia 

 solium removed from their cysts, (1) natural size, (2) magnified; a, 

 proscolex ; 6, proscolex with hooks and suckers, c. 



testine, attaches itself by means of its hooks and suckers to the 

 mucous membrane, becomes solid, and develops a chain of pro- 

 glottides. The bladder worm was not at first known to be a stage 

 in the life-history of tapeworm, and hence received a special generic 



Fig. 13. TAPEWORM (from Landois and Stirling). Cysticercus of Tsenia 

 solium with everted scolex : a, proscolex ; 6, head with hooks and 

 suckers ; c, neck. 



name, Cysticercus, the particular one belonging to Taenia solium 

 being known as Cysticercus cellulosce. 



Those who regard the tapeworm as an example of alternation 

 of generations, recognise three stages in its life-history, two 

 asexual (proscolex, A; scolex, A'), and one sexual (proglottis, S), 

 the cycle being A A 7 S. 



