212 ANIMAL PARASITES AND MESSMATES. 



separately. In the eestodes all these individuals are 

 united in a kind of band, and are besides this joined 

 to the mother, which becomes the root of the family. 

 This root, planted in the walls of the intestine, is the 

 head. Thus each segment of the taenia is an individual, 

 and at the period of sexual maturity, this individual is 

 detached, goes away with the feces, spreads over the 

 grass or elsewhere, and thus sows far and wide the eggs 

 which it contains. 



The taenia, as well as the other tape-worms, is generally 

 looked upon as an imprisoned parasite during the whole 

 of its existence. This is a mistake ; the last stage of the 

 life of eestodes is a phase of liberty. The cucumerina, 

 or, as we have proposed to call it, the proglottis, that 

 is to say, the complete and sexual animal, is evacuated 

 with the feces : and when we notice a dos^ leavino^ ■ 

 his dung upon the grass, it is not nncommon to see 

 there worms which move like leeches, and whose white 

 colour is in strons; contrast with the mass which 

 contains them. The duration of this last stao;e is verv 

 short, it is true ; but it is, nevertheless, during this 

 period of her life that the mother scatters the eggs 

 which are to disseminate the species. 



We repeat that each animal has its parasites, and 

 these in their turn are not always exempt from them. 

 We have already cited some examples of this. 



Man has the dental system of a veo^etable feeder ; 

 but, thanks to fire, which he alone knows how to produce 

 and maintain, he eats flesh. It is bv tliese means that 

 lie nourishes the solitary worm, wliich, by its crown 

 of hooks, IS a cestode belonging to the carnivora, and 

 the TcBuia mediocanellata with the Botriocephalus^ which 



