64 WORM PARASITES. 



of the worm ; they become, as it were, ripe. Each 

 proglottis has male and female organs of its own 

 and can fertilize itself. The last mature segments 

 are full of ova (fig. 20). Although each segment is 



Fig. 20. 



a 

 l 



Ovum and embryo of a Tapeworm. 



apparently sexually distinct, yet nevertheless all the 

 proglottides are united by a system of water or ex- 

 cretory tubes, and are supplied possibly by the same 

 nerves. 



The Tapeworm has no mouth and no alimentary 

 canal. Its food is gained by absorption through 

 the skin, a kind of osmosis. 



The Tapeworm is the sexually mature form of 

 Cestode, and always lives as a parasite in some part 

 of the intestines, to the mucous membrane of which 

 it anchors itself on by the hooks and suckers above 

 referred to. The ripe proglottides full of eggs are 

 passed out in the faeces, and in many cases get into 

 water. This completes the first stage of Tapeworm 

 existence. 



The second stage is passed in quite a different 

 'host/ and in various organs, generally causing 



