"GROUSE DISEASE "—PATHOLOGY 301 



always associated with grave changes in the mucous membrane of the caecum ; 

 and concurrently with these changes intestinal bacteria, particularly those 

 belonging to the Bacillus coli group, find their way into the liver, or even 

 into the other organs. We have determined by actual worm counts and 

 cultures that Bacillus coli is always absent from the liver (in birds examined 

 immediately after death) when there are no Strongyli (hand-reared birds) or 

 only very few (not exceeding one hundred in numl:)er). When more than 

 one hundred but less than one thousand are found, Bacillus coli is some- 

 times present in, and sometimes absent from, the organs, but when the numbers 

 of Strongyli exceed one thousand, then Bacillus coli is always present 

 in the liver, and occasionally in the other organs. 



We have not been able to satisfy ourselves that the bacilli which find 

 their way into the organs do much harm. Some harm no doubt they do, 

 but how much we cannot say. Microscopic examination has not revealed 

 any profound changes in these livers. The numbers in which these bacteria 

 penetrate into the organs is difficult to estimate because, doubtless, they 

 soon get killed in the living tissues, so that the numbers of colonies cultivated 

 must bear only a small proportion to the total number of bacteria which 

 have entered the fragment of tissue examined. The number of living bacilli 

 in the organs of these Grouse is undoubtedly small ; from which it is evident 

 that they do not multiply in the organs. " Grouse Disease " is therefore 

 not an infection with these bacteria. Is it a toxaemia caused by the poison 

 liberated from bacteria which have been absorbed from the intestine, and 

 which have almost immediately perished in the tissue ? We know that in 

 order to produce serious mischief in animals by a single injection of dead 

 bacteria a considerable quantity must be employed ; and it is difficult to 

 believe, when we remember the small numbers of colonies which grew on 

 our cultures, that relatively to this quantity the numbers of bacteria absorbed 

 could have been very large. On the other hand, we have little information 

 concerning the influence of the constant absorption of small numbers of 

 bacteria, but this is believed by Adami and his school to be a potent source 

 of disease. The fact that we have repeatedly found Bacillus coli in the 

 livers of " normal " birds badly infected with Strongyli, prevents us from 

 ascribing the death of the Grouse directly to these bacilli, though they 

 probably play some part. 



It seems to us quite certain that the Strongylus when exceptionally numerous 



