88 ANIMAL PARASITES AND MESSMATES. 



among paupers when they are in their infancy or at the 

 ajDproach of adult age, for they only seek for help at 

 the beginning or towards the end of their career. These 

 are very numerous, and more than one species change 

 their dress so completely that they can no longer be 

 recognized. Finding with their host both food and 

 lodging, they throw off their fishing and travelling gear, 

 settle themselves comfortably in the organs which they 

 have chosen, and having got rid of the baggage which 

 connected them with the outer world, preserve only their 

 sexual organs. 



As to the rank which these parasites occupy in the 

 scale of being, it may be said that there is no especial 

 class of iDarasites ; and worms are not distinguished in 

 this respect, except by having a greater number of species 

 subject to this rule. All classes among invertebrate 

 animals include parasites. 



It is also an error to suppose that the whole species, 

 the young as well as the old, the males as well as the 

 females, are always parasites ; often the female, not being 

 able to provide for the necessities of life, seeks for food 

 and shelter, while the male continues his nomad life. 

 Therefore the female alone puts on the pauper's dress, and 

 by a recurrent development, assumes sometimes such 

 a singular appearance that the male no longer resembles 

 her. One cannot say that the females constitute the 

 heau sexe in this group, since they are often so monstrous 

 in form and size that their appearance has nothing in 

 common with a perfect animal ; their body is deprived oi" 

 all its exterior organs, and there often remains only a 

 skin in the form of a leather bag, without any distin- 

 guishing character. 



