"GROUSE DISEASE" 159 



the intestine at the moment when the normal defence had 

 broken down. 



It gradually began to dawn upon the Committee that the 

 appearances in the lung upon which Klein had relied in making 

 a diagnosis of acute infectious pneumonia differed in no way 

 from the appearances which had been observed by the Com- 

 mittee in the lungs of hundreds of birds found dead from all 

 causes, including Cobbold's Strongylosis, general Helminthiasis, 

 accidents, or even shot wounds. 



This discovery undermined the faith which the Committee 

 were prepared to place in the existence of Klein's acute infectious 

 pneumonia, and it soon became evident that in birds obviously 

 dying of " Grouse Disease," there was no dangerous ante-mortem 

 infection of the lung or other tissues with the bacillus in question, 

 and no recognisable lesion in any organ of the bird except in parts 

 of the intestine. All the appearances which were previously 

 attributed to Klein's pneumonic disease, were now found to 

 be due to post-mortem change alike evident in diseased and in 

 perfectly healthy normal birds. 



The point was further tested by taking a number of healthy 

 pigeons, and killing the whole of them at the same time with 

 chloroform. The birds were numbered and opened on consecu- 

 tive days and the change in the appearance of the viscera 

 was noted. It was evident that in every case where there 

 had been extravasation of blood or serous fluid owing to rough 

 handling, or damage by the knife in dissecting the pigeon, the 

 tissues of the lung became black, and took upon themselves 

 precisely the same appearance that is seen in a Grouse found 

 dead upon the moor, or examined some days after being shot. 

 The appearance of pneumonia was evidently due to a soak- 

 ing of the lung-tissue in decomposing blood and serum, and 

 the post - mortem colonisation of the tissues by Bacillus 

 coli. 



Once this fact became clear, the Committee was no longer 

 burdened with the task of recognising and investigating the 

 type of " Grouse Disease " described by Professor Klein, for it 



