10 



been shown both experimentally and on the 

 moor that the cysts pass through the bodies 

 of both maggot and fly undigested and un- 

 harmed. 



The second disease which the Inquiry has 

 found responsible for grouse epizootics 

 observed between 1905 and 1910 is one to 

 which Cobbold drew attention in 1873, 

 though he attempted little in the way of 

 pathological investigation. According to him 

 it is caused by the presence of a round worm 

 now known as Trichostrongylus pergracilis, in 

 the caeca. We may call the disease " Strongy- 

 losis of the grouse." The worms are minute, 

 transparent, very slender, a little less than half 

 .an inch in length, and they may exist in enor- 

 mous numbers, 10,000 occurring in the two 

 caeca of one bird. They are about equally 

 divided between the two blind-guts. We may 

 recall the fact that in the grouse the caeca 

 are of unusual size, and that in these birds the 

 digested food is absorbed in this region of the 

 alimentary canal alone. 



Birds heavily infected with T. pergracilis 

 show an inflammation of the walls of the caeca, 

 the contents consist of dry masses very adherent 

 to the walls, and to these hard masses at one 

 end and to the mucous lining at the other the 

 worms adhere. It appears as if these masses 

 have been for long retained in the caeca without 

 either being absorbed or passed along. The 

 ridges of the inside of the caeca are found to 

 be thickened, especially in the neighbourhood 

 of these dry masses. The villi are swollen or 

 wasted ; in some cases the lining membrane, 

 normally smooth, resembles, when seen under 

 -a microscope, masses of coral. Sectiors 

 through the caeca in badly infected birds show 



