64 



DlSKASrS Ol- rOTLTRV. 



air -sac mite show no symptoms of disease, and the ex- 

 istence of the parasite is only discovered accidentally 

 when the carcass of a bird which has died from some 

 other cause is being examined. In other cases the 

 fowls are listless, 

 inactive, with pale 

 comb, and loss of 

 flesh. Occasional- 

 ly one dies without 

 anyapparent cause. 

 The acute cases 

 may come on with - 

 out premonitory 

 symptoms. The 

 affected birds are 

 found quite ill, 

 standing by them- 

 selves, with neck 

 retracted, wings 

 drooped, and la- 

 bored breathing. 

 There may be rattling of mucus in the throat as 

 in bronchitis, or paroxysms of coughing. Death may 

 come suddenly from obstruction of the air -tubes with 

 plugs of mucus, or in other cases the illness may be 

 prolonged and the birds die of exhaustion. 



The mites are readily discovered on the walls of the 

 air-sacs after the death of the bird. They are about 

 one-fiftieth of an inch in length and, therefore, easily 

 seen with the naked eye. They are often so numerous 

 that the surfaces of the air -sacs appear as though dust- 

 ed with a whitish or yellowish powder. By careful 

 watching, the points of which this powder is composed 

 are seen to move and may be made out as the indivi- 



Fifr. \2.—Cytodites Niidut, female. 



