62 



DISEASES OF POULTRY. 



sitism which is not seen in our other domesticated 

 animals. One of the mites has domiciled itself in the 

 air-sacs of the gallinaceous birds, especially in poultry 

 and pheasants, and is found at times in great numbers 

 even in the abdominal sacs and in those which pene- 

 trate the bones. This mite, called the Cytodites nudus, 

 is closely related to those mites which live upon the 

 skin and cause mange or scabies. Indeed, when first 

 discovered it was supposed by Gerlach to be one of 

 the mange insects and to cause an internal form of 

 that disease. 



Careful study has shown that while the Cytodites is 

 closely related to the 

 mange acari, it differs 

 from them in very im- 

 portant characters. The 

 mouth parts in the 

 mange mites are formed 

 to cut and tear the flesh 

 and enable the mite to 

 burrow into the skin, or, 

 at least, to puncture the 

 skin and obtain blood 

 or serum for its suste- 

 nance. In the air -sac 

 mites the mouth parts 

 are grown together and 

 form a tube through which liquids may be sucked, but 

 which is not adapted for tearing or puncturing the 

 flesh. It would appear, therefore, that these mites can 

 only produce a superficial irritation by their presence 

 and movements upon the delicate surface of the mucous 

 membranes, or possibly by depositing a virulent saliva 

 such as is supposed to be the cause of a part of the 



Fig-. 12. — Cytodites iiudiLs, male. 



