ANATOMY AND PHYSIOLOGY OF RED GROUSE 173 



resulting from shot wounds, collision with wire fences or similar 

 accidents. This subject has already been dealt with. 1 



By far the more important pathological changes which are 

 to be found in the Red Grouse are those which result from ex- 

 cessive parasitism, and they are therefore discoverable as a 

 rule in the intestines, and above all in the two blind caeca, 

 which afford a habitat to thousands of the round- worm Tricho- 

 strongylus pergracilis. The particular damage caused by this 

 threadworm resulting in the fatal Grouse disorder which is now 

 called Strongylosis, will be dealt with in chapter viii. 2 



It will best serve the purpose in view to take again the 

 alimentary tract from end to end, and to mention the lesions 

 to which the various parts are liable. 3 



It is a very rare thing to find any disturbance in the upper 

 reaches of the alimentary canal. The mouth, the oesophagus, 

 the crop, the proventriculus, and the gizzard as a rule carry no 

 parasites, and are very seldom the seat of any pathological 

 trouble. But it may happen that a bird gets hold of some 

 irritant poison with its food, and this probably accounts for 

 one or two otherwise unaccountable cases of inflammation of 

 the crop walls, with engorgement and enlargement of all the 

 vessels ramifying over it. 



In the duodenum it is comparatively common to find the 

 lining intensely inflamed, showing a bright red surface to the 

 naked eye, sometimes all over, and at other times in patches. 

 This is apparently the result sometimes of the presence of the 

 tapeworm Hymenolepis microps, in large numbers ; sometimes 

 of the presence of the threadworm Trichosoma longicolle. But 

 although in many cases the lining is thus reddened and 

 Hymenolepis and Trichosoma are abundant, it is 'also quite as 

 frequently found that the worms are present without any 

 reddening, and in some cases reddening is present without any 

 sign of a worm. 



It is probable that in many of these cases where there is 



1 Vide chap. iv pp. 119 et seq, 2 Vide chap. viii. p> 204* 



3 Vide Diagram, p. 165, 



