THE AIR SAC MITE OF THE FOWL. 
9 
post-mortem appearances consisted chiefly of a diffuse enteritis, 
the posterior bowel being- chiefly inflamed, and co-existent with 
this there appeared on the transparent membranons walls of the 
air sacs about the intestines, niimerons minute opaque appearing 
objects, which, upon examination, proved to be air sac mites. 
Inquiry being instituted, it was learned that poultry-raising 
in Montana was generally unprofitable, owing to frequent heavy 
losses, largely from a malady simulating in symptoms that which 
was engaging my attention, so that with numerous natural ad¬ 
vantages as to food and climate, the major portion of poultry 
and eggs consumed in the State was imported from a long dis¬ 
tance at high rates, and deteriorated in quality because of the 
long shipment. 
It was further ascertained that the monetary loss in the Gal¬ 
latin Valley, the most important agricultural area in the State, 
was quite as great from poultry diseases as from those of any 
other kind of domestic animals, and as far as could be learned, 
it seemed that the most serious and persistent malady of poul¬ 
try was that due to the air sac mite. 
The literature obtainable in other languages indicates that 
various investigators ascribe to this parasite a considerable eco¬ 
nomic importance, but none of them attribute to its presence 
the gravity which it attains in Montana and perhaps some 
neighboring Rocky Mountain States. 
The disease was first studied by Gerlach,* who relates that 
in 1858 his attention was called to a fatal affection in a flock of 
a few more than twenty Cochin China fowls, among which in a 
short time twenty died, which upon post-mortem examination 
revealed extensive muco-enteritis and inflammation of the ovi¬ 
ducts, and in the bronchial tubes and their dependencies, the 
air sacs, he found numerous small mites, either solitary or in 
clumps. Although Gerlach could not directly connect the en¬ 
teritis with the presence of the parasites, he could find no other 
cause for it and concluded that they were in some manner re¬ 
sponsible for the fatal lesions. 
* Magazin fur die gesammte Thierheikunde, 1859, p. 233. 
