348 



THE DOG IN DISEASE. 



from the head end, and which contain both male and 

 female generative organs ; so that a tape- worm is an exam- 

 ple of an animal in which the sexes are combined ijier- 

 maphrodite). When each segment is perfect, it produces a 

 vast number of eggs and drops away from the main 

 colony. Those farthest from the head, being the oldest, 

 come away first. 



When these segments find their way into certain ani- 

 mals the eggs are set free by digestion of parts surround- 



FiG. 32.— Head of Both- 



RIOCEPHALUS LaTUS 

 MAGNIFIED (StONE- 

 HENGE). 



Fig. 33. — Head of 

 T.ffi;NiA Solium 

 magnified (aft- 

 er Heller). 



Fig. 34.— Head of T.e- 



NIA MeDIOCANELLATA 



magnified (after 

 Heller). 



ing them. The eggs hatch out into embryos, which under- 

 go development up to a certain point, but do not become 

 tape-worms in that species of animal but usually migrate 

 from the alimentary canal into some other organ, com- 

 monly the liver, there forming often hydatids, or cysts, 

 and proving fatal to their host. But when these hydatids, 

 or immature tape-worms, pass into that particular species 

 of animal suitable for their development they become 

 tape-worms. 



