46 ANIMAL PARASITES 



seven days. Probably one egg is laid every day. I 

 Now, it must be remembered that the skin is con- 

 stantly wearing off, and as constantly renewed by 

 new growth from beneath ; hence, as will be seen 

 by these illustrations, the eggs hatching in the 

 furrow will come to the surface in time for the 

 animal to escape from its shell when fully formed. 

 These canals which the female acari burrow, have 

 generally a serpentine form, and are from a 

 twelfth to a quarter of an inch in length. They 

 show on the surffice of the skin a whitish dotted 

 appearance, the dots corresponding to the eggs — 

 the female, as seen in the cuts, being at the bJuid 

 end of the burrow. Ignorance or forgetfulness of 

 this fact has been the cause of the itch-mite escap- 

 ing detection. There v/ill l^e a little pimple or 

 vesicle on the skin over where the mite went in ; 

 and, as we see from these figures, the animal is 

 not there, but off at some distance deeper in the 

 skin ; hence, if we open the little vesicle, or cut it 

 out, the insect escapes us. The old women in 

 Corsica, and other parts of the world, knew bet- 

 ter, and with a needle dug out the acarus from the 

 end of the burrow. A surer way of obtaining it, 

 and the whole burrow, is to clip this off with a 



