14 THE GROUSE DISEASE chap. 



infectious pneumonia. In the severe forms, such as 

 are observed during epidemics in May and June, 

 the birds, once affected, rapidly, in a day or two, 

 show great loss of muscular power and seek the 

 water. The loss of muscular power is apparent by 

 the impeded flight, this being sluggish, being per- 

 formed with unwillingness, and not for any normal 

 time, that is to say, if on the wing the birds soon 

 drop again. Wherever there is a trace of water the 

 affected birds will seek this, and in many instances 

 in severe epidemics their bodies are picked up in 

 numbers on the shores of such water. As the post- 

 mortem examination shows, the congestion of the 

 lungs forms a conspicuous pathological symptom ; 

 and it is therefore clear that, as in acute congestion 

 of the lung in man and animals, also in the grouse, 

 under these conditions, fever must be a prominent 

 symptom, and the above appearances during life 

 easily account for this. 



Also the peculiar -alteration in the call of the 

 diseased birds, this being somewhat feeble and 

 hoarse, would be a natural result of the lung con- 

 gestion, since this condition would prevent the birds 

 from uttering their call with normal force, and the 

 congested state of the mucous membrane of the 

 larynx would cause the sound to be less clear and 

 sharp, and more hoarse. The more or less ruffled 



