34 



THE MICROSCOPE. 



the body may be seen small circular dots, the breathing 

 apertures, with which all the class are freely provided, 

 rendering them very tenacious of life, and difficult to kill. 

 There is another louse, rather differing in its characteristics 



Fig. 289. 



1, Bog's parasite. 2, Rat Acarus. 3, Head of Cat-Flea. 4, Larva, or; grub ol 

 Flea, (The life size of each is given in the small circles.) 



