i3& a:^imal parasites a.nd messmates. 



CHAPTER VII. 



PAEASITES FREE WHILE YOUNG. 



We have brouglit together in the former chapter the 

 animals which live at the expense of their neighbours, 

 without seeking for anything except shelter. They seize 

 their prey as they pass, are nourished by the blood of 

 their neighbours, but never think of establishing them- 

 selves in their organs during any period of their life. 

 They are almost as much carnivora as parasites, and 

 only differ from the former, class because they spare the 

 life of their victims. They are unlike ordinary parasites, 

 since they are contented with their food alone ; and their 

 appearance from the period of theii* entrance into the 

 world is that of free animals. Those whose history we 

 are now about to sketch, live in freedom like the preced- 

 ing during all the time that they are young ; like them, 

 they are completely independent during the first period 

 of their life ; but when they have arrived at mature age, 

 when the endless cares entailed by their young ones come 

 upon them, they chaijge their costume and accommodate 

 themselves as well as they can to the new lodging which 

 they have chosen. There is often not the least resem- 

 blance between these creatures in their youth and their 

 adult state. All these parasites have lived a joyous life 



