NATURE OF THE DISEASE 



severe, is independent of the presence of strongylus. 

 I dissected numerous birds dying or dead of the 

 disease in 1887, and showing the characteristic lung 

 change, and must confess that I was extremely sur- 

 prised to find the strongylus in some cases entirely 

 absent, in others present in very small numbers, 

 though taenia calva was present in all in large num- 

 bers, just as large as in birds killed but not affected 

 with the grouse disease. 



Amongst various writers on the grouse disease, none 

 deserve a higher place than Dr. H. Colquhoun and 

 Dr. D. G. F. Macdonald. By selecting the opinions 

 of these two writers amongst a host of writers who, 

 by letters to the Times and th.& Field or other publica- 

 tions, have contributed to this question, I am practi- 

 cally quoting, in a condensed form the most note- 

 worthy summary of the various opinions offered. All 

 these opinions as to the cause of grouse disease do 

 not in reality touch the causa causans at all, but 

 the conditions or secondary causes, which favour, and 

 play an important part in, the appearance of the 

 grouse disease in the epidemic form. Amongst these 

 conditions may be mentioned: — {a) bad season; 

 {b) bad or insufficient food; and {c) overstocking. 

 It must be obvious that as in many other acute in- 

 fectious disorders amongst men or animals these 

 conditions play a very important part, 'inasmuch as 



