CHAPTEE X. 



PARASITES DURING THEIR WHOLE LIFE. 



isr this chapter we bring together true parasites, which 

 may be called complete ; they pass every part of their 

 life under the care of a neighbour, and require an asylum 

 the more urgently, since they cannot exist without it. 

 They absolutely need both food and lodging. Not long 

 ago, all parasites were supposed to be dependant during 

 their whole life, and to be incapable of living outside the 

 body of another animal. We have before proved that 

 this opinion was erroneous. We find in this category a 

 great number of parasites which may be separated and 

 placed in the first group, including all such as pass all 

 the phases of their life on the same animal, without 

 changing their costume, and many of which never leave 

 the fur, the feathers, or the scales, among which they are 

 born. 



Fishes nourish on the surface of the skin a great 

 number of these, which helminthologists have thought 

 proper to classify under the name of Ectoparasites. 

 Among many crustaceans and insects, only one of the 

 sexes is parasitical. The males remain entirely free, 

 and preserve all their attributes, while the females seek 

 for assistance, and require food and lodging. The female 



