160 THE GROUSE IN HEALTH AND IN DISEASE 



now became impossible to accept his explanation of the disease. 

 It then became necessary to set on foot more detailed investiga- 

 tions to determine the following points : 



1. To prove that the amended view of Klein's work was 



the right one, and that the " Grouse Disease " which 

 he saw and described as a form of infectious pneumonia 

 was in reality not different from the " Grouse Disease " 

 which the Committee were seeing constantly, and were 

 describing as Cobbold's Strongylosis. 



2. To make a complete investigation of the life history of 



the Trichostrongylus pergracilis or the Strongyle of 

 Cobbold, with a view to ascertaining its mode of infect- 

 ing Grouse, its action in the caecum of the Grouse, its 

 method of reproduction, its dissemination, and the con- 

 ditions which enable it to hatch from the egg, to pass 

 through the stages of development, to survive on a 

 Grouse Moor, and to enter a bird at a stage when to be 

 swallowed means completing the cycle of parasitic life, 

 instead of being merely digested. The life history of 

 this threadworm was obviously required in its smallest 

 details, in order that Strongylosis might be understood. 



3. To discover whether this or any other form of " Grouse 



Disease " was caused by bacterial infection or not. 

 For convenience this may be called the bacterial theory. 



4. To investigate the blood of the Grouse in health and in sick- 



ness, and especially to try and discover whether death was 

 caused by toxins introduced by parasites in the intestine. 

 This might be known as the "blood-poisoning" theory. 



5. To make certain that " Grouse Disease " did not result 



from the presence in the intestines, or in the blood, 

 of any protozoal parasite. This might be called the 

 protozoal theory. 



6. To complete the investigation of the Grouse parasites, 



ectozoa as well as entozoa, with a view to determining 

 whether " Grouse Disease " could be considered attribut- 

 able to some of them, or even to one of them. 



