44 ANIMAL PARASITES 



itan and Egyptian sheep, and the ferret. It has 

 been thought, also, that the mites found in many 

 other animals are the same as man's irritating com- 

 panion, their growth being favored or retarded by 

 their place of development, thus accounting for 

 the apparent difierences in shape and size. The 

 itch-mite lives in the skin, in little passages dug 

 by itself, or, sometimes, just beneath the epidermis 

 or scarf-skin. These burrows the animal makes 

 extend into the deeper layers of the epidermi.^, 

 down to and into the true skin, or rete mucosun}, 

 as it is called. The acariis moults three times, 

 not, how^ever, specially changing in form. The 

 eggs are oval in shape, quite large for the size of 

 the animal, and may be laid by the female to tlie 

 number of fifty. AYe give here three drawings, 

 to show how the animal gets into the skin to form 

 the burrows, now called " acarian furrows" by 

 dermatologists. 



In Fig, 5 the mite has got down beneath the 

 epidermis. In Fig, 6 it has commenced digging 

 the burrow longitudinally, and the place (/") where 

 it was in Fig. 5 has, by the gradual growth of the 

 cells, come up nearer to the surface of the skin. 

 In Fig, 7, the point (/) has thus come u^ to the 



