126 



ANIMAL PAEASITES AND MESSMATES. 



constituted a pathological condition, two errors which 

 have now -been recognized, and by which the science of 

 medicine has profited. 



The Phthirius pubis is another species which has been 

 found only on white races, and attaches itself especially 

 to the hair on the pubis. Mons. Grimm has published 

 in the bulletins of the Academy of St. Petersburg, an 



Fig. 18. — Louse of the Head* 2, 3, sucker. 



Fig. 19.— Louse of the Head, claw. 



interesting memoir on the embryogeny of this insect ; 

 and, more recently, Mons. L. Landois, of Griefswald, 

 has completely studied its habits. 



We are now about to refer to certain parasitical 

 insects whose name is usually associated with those 

 which have preceded ; they are well known by all, and 

 attack both men and the mammalia with no less 

 ferocity ; we allude to fleas, which differ from gnats in 

 this respect, that the male is as eager for blood as the 

 female, and that both of them, like leeches, live by 

 sucking it; besides, the larvae of fleas live only on what 



