6 THE GROUSE DISEASE chap. 



(Cobbold, Parasites, p. 439) "the occasional presence 

 of numerous tape-worms {Tcenia calva) hastened the 

 consequent fatality." This view has always been 

 strenuously opposed by various writers and observers, 

 both lay and veterinary or medical, inasmuch as it 

 was considered quite insufficient to account for the 

 disease ; for it was pointed out by Dr. Farquharson 

 and Mr. Wilson (see below), and can be easily veri- 

 fied, that the same parasites occur also in birds not 

 subject to the disease. Now, taking into consideration 

 that the disease is well characterised both in its symp- 

 toms and its pathology ; that the same parasites un- 

 doubtedly occur in grouse not afflicted with the grouse 

 disease ; that grouse dead of the disease are found 

 sometimes plump, sometimes emaciated ; and, above 

 all, that grouse dead of the disease, in several instances 

 when examined, showed no presence of the stron- 

 gylus : it must be evident that the parasites some- 

 times present in the intestine cannot be the real cause, 

 the causa causans, of the disease. That cause must be 

 of a different nature. It must be of a nature which 

 works rapidly, or fairly rapidly, which affects the 

 system as a whole, and which easily spreads amongst 

 the birds. We shall presently see that one of the 

 most prominent pathological changes in the diseased 

 grouse is an acute congestion of one or both lungs, 

 and that this change, whether very severe or less 



