^2 ANIMAL PARASITES 



of care and importance. So also with the com- 

 mon flesh-fly, musca carnaria. They thus add 

 greatly to the misery of certain endemic diseases, 

 as the aflections of the eye in Egypt. The house- 

 fly may also deposit its eggs, and its larvae be 

 found in wounds, and the orifices of the body. 

 The eggs and larvae of the bot-flies may live on 

 the skin, and there form boils. In South Amer- 

 ica this parasite is reported as by no means rare 

 upon man. Von Humboldt called it cestnis hu- 

 maniis. It is not yet, however, settled whether 

 this is difierent from the bot of the horse, sheep, 

 ox, stag, and other bot-flies. Fluctuation will be 

 sought for in vain in the tumors produced by 

 them, but an orifice will be found in the swelling, 

 from which a little moisture constantly oozes, and 

 through which the hinder part of the cestrus is . 

 kept in communication with the air. The prog- 

 nosis is favorable, and immediate cure is only pos- 

 sible by incision, and the removal of the cestrus. 



The Medina-worm, or Guinea hair-worm , /?/a- 

 7'ia onedinencis, is an inhabitant of another por- 

 tion of the world, and need not, therefore, be dis- 

 cussed here. On the other hand, we must take 

 some notice of the sand-fiea, pulex penetrans, since 



