274 THE (4 ROUSE IN HEALTH AND IN DISEASE 



Our work has been done both with diseased and healthy birds. The 

 former were caught by the keepers in a feeble or dying condition, at times 

 Specimens ^hcn dead birds were being picked up in considerable numbers on 

 Grouse^***^*^ the moor, and it was consequently believed that "Grouse Disease" was 

 examined, prevalent. But the mortality then was, we believe, not very great, 

 in fact insignificant when compared with the really bad years such, for 

 example, as 1873, and it is, we suppose, just possible that we never came 

 across the genuine epizootic "Grouse Disease" at all. 



The diseased birds which were subjected to bacteriological examination 

 were nearly all caught alive and brought or sent to the temporary laboratory. 

 Some, of course, died on the journey, but in only a few preliminary instances 

 were cultures made from the latter, and then only when it was exactly 

 known when the bird was last seen alive. 



In addition to these birds from which cultures were made, many others 

 which were picked up dead were examined for lesions and gross parasites. 

 As will be easily understood the difficulty of obtaining diseased birds alive 

 was very great, and the number fully investigated therefore very small. 



The control observations on normal birds were more numerous ; for, through 

 the kindness of the members and correspondents of the Committee and others, 

 we had no difficulty in obtaining as many as we wanted. Some 

 observa- few of thcsc wcrc examined in Scotland, but the great majority 

 were received alive in our laboratory at Cambridge. A considerable 

 number of these were caught for us by the keepers, and since it is no doubt 

 easier to catch a feeble bird than a strong one, it may be that they do not 

 fairly represent the average normal bird. It is probable, however, that they 

 do not fall far short, if at all, of this standard, for they were plump and of good 

 weight. They, of course, contained numerous entozoa, as do also the strongest 

 birds which fall to the gun. The rest were hand-reared birds kept in captivity. 



The first to attribute " Grouse Disease " to a living parasite was, we believe, 



Cobbold^ (1873) who drew attention to the presence of the small 

 Cobbold. ^ ' . ... 



nematode worm, Trichostrongylus pergracilis, often in large numbers 



in the caeca of Grouse which were supposed to have died of the disease. 



Nineteen years later Klein ^ (1892) investigated the disease, and came 



to the conclusion that it was "an acute infectious pneumonia" caused 



' The "Grouse Disease," tlie Field Office, London, 1873. 



- "The Etiology and Pathology of Grouse Disease, Fowl Enteritis and some other Di.^eases affecting 

 Birds." London : Macmillan & Co., 1892. 



