220 THE GROUSE IN HEALTH AND IN DISEASE 



by the poison liberated from bacteria which have been absorbed 

 from the intestine, and which have almost immediately perished 

 in the tissue ? We know that in order to produce serious 

 mischief in animals by a single injection of dead bacteria a 

 considerable quantity must be employed ; and it is difficult 

 to believe, when we remember the small number of colonies 

 which grew on the cultures, that relatively to this quantity 

 the numbers of bacteria absorbed could have been very large. 

 On the other hand, there is little information concerning the 

 influence of the constant absorption of small numbers of bacteria, 

 but this is believed by Adami and his school to be a potent 

 source of disease. The fact that Bacillus coli has been repeatedly 

 found in the livers of "normal" birds, badly infected with 

 Strongyles, prevents us from ascribing the death of the Grouse 

 directly to these bacilli, though they probably play some part. 

 If these are really numerous, their products will doubtless exert 

 some amount of harmful influence, but how much we are not at 

 present in a position to say. The fact that no important lesions 

 have been found either by macroscopic or microscopic examina- 

 tion in the livers which have yielded cultures justify the view that 

 the bacilli play only a secondary part in the causation of death. 

 From the foregoing remarks it will be seen that the case 

 against the nematode, or round worm Trichostrongylus pergracilis, 

 is fairly clearly established, for though this parasite is seldom 

 entirely absent from healthy birds, its presence in large numbers 

 in the caecum is usually associated with definite lesions. Tricho- 

 strongylus probably does little harm if not present in too great 

 numbers. With regard to the presence of the worm in large 

 numbers in some of the birds caught on the moor, and supposed 

 to be healthy birds, it must be remembered that strong wild 

 Grouse are difficult to catch, and that some at least of the 

 methods of capturing Grouse alive seem calculated to catch the 

 weaker birds rather than the stronger ones. On the other 

 hand, on counting the Strongyles in a number of " normal " 

 and diseased birds, there has been found a great difference 

 between the two classes, very large numbers being always found 



