200 THE GROUSE IN HEALTH AND IN DISEASE 



but, in the days when he was working at the subject, no one could have 

 arrived at other conclusions than those to which he himself came. It is due to 

 so great and careful a worker to say that at that time he was years ahead of any 

 other bacteriologist. That he should since have been found to be in error 

 merely shows how dependent is science upon the methods available at the 

 moment, and how impossible it is for any one at any time to be certain that 

 even the most probable explanation of observed facts is the right one. 



It has been thought necessary to set forth the different stages of opinion 



through which the Committee has passed in order to account for many 



mittee's provisional conjectures, since shown to be faulty, as to the cause of 



diagnoses death in birds that were submitted for examination in the earlier 



incorrect. -, /, , , T 



days oi the Inquiry. 



From the first it was thought advisable to acknowledge the receipt of every 

 bird sent to the officials conducting the Inquiry, and, where possible, to account 

 for its death or its sickness, or for any abnormality which it presented. 



In the earlier days the field-observers believed firmly in Klein's view that 

 " Grouse Disease " was an acute infectious pneumonia, and in a few isolated 

 cases they believed that the lesions described by him with so much detail 

 were present. They thereupon made the necessary diagnosis and sent in their 

 report, and for the next week or two awaited an inundation of dead birds 

 showing similar lesions. But no epidemic occurred and the inundation did 

 not happen, and by degrees it became evident that there was something doubtful 

 about the view which had been provisionally adopted. 



This doubt was confirmed when the bacteriologist, Dr Seligmann, found 

 that the bacillus which Professor Klein considered to be the specific cause of 

 Klein's Grouse pneumonia was in fact only to be discovered in any number 

 foundtobe some twelve or twenty-four hours after death. It became gradually 

 ^rtem P St c l ear tna * no ^ or ^J ^ e g rosser appearances in the lung which Klein 

 change. considered to be due to pneumonic congestion, but the microscopic 

 appearances of the lung - tissue in section, as well as the colonies of bacilli 

 which he described and figured in the lung, were in fact only to be found some 

 hours or days after the death of the bird. They were undoubtedly due to a 

 post-mortem migration into, and colonisation of, the tissues in question by 

 numbers of Bacillus coli which had escaped from their proper sphere in the 

 intestine at the moment when the normal defence had broken down. 



It gradually began to dawn upon the Committee that the appearances in 



