II SYMPTOMS AND PATHOLOGY 15 



condition of the feathers of the back and throat, 

 or rather the absence of the smooth condition and 

 metallic lustre of the feathers of the back observed 

 in diseased birds, could also be accounted for by 

 their feverish condition. 



The colour of the eyelids, bright in the normal 

 state, is not of the normal bright orange colour in 

 birds dead of the disease. In every severe congestion 

 of the lungs, such as obtains in the severer forms of 

 the grouse disease, there is a general venous conges- 

 tion of all parts consequent on the engorgement of the 

 venous part of the heart supplying the pulmonary 

 artery ; and therefore also the skin all over the body, 

 including the eyelids, would participate in this venous 

 congestion. The natural aspect of the bright pigment 

 of the eyelids would therefore become altered by the 

 presence of this venous congestion, and the eyelid 

 would look duller. 



Pathological appearances. — The birds that die dur- 

 ing a severe epidemic, such as obtains in the spring 

 and early summer, show the following post - mortem 

 appearances : the crop is generally more or less full 

 of undigested heather ; as a rule this is the more 

 conspicuous the better nourished and the plumper 

 the bird, and the better preserved the pectoral 

 muscles are. I have dissected birds which were 

 emaciated, the legs bare of feathers, and in which 



