148 THE GROUSE IN HEALTH AND IN DISEASE 



worm to the bird being compelled to eat unwholesome food, from its natural 

 food the heather being damaged or destroyed from continued blighting east 

 wind ? And thus the blight of the heather is really at least one cause of 

 ' Grouse Disease."' 



"Insufficient or unwholesome food is the cause at least of one type of 

 disease amongst Grouse." 



Or the following : 



"'Grouse Disease' is caused mainly by overstocking, over-preservation, 

 and the complete and indiscriminate slaughter of certain species of so-called 

 vermin, notably the Peregrine Falcon ; also by the state of the young and 

 old heather after severe and late frosts which do much more harm now that 

 heather burning is done systematically. Also by greed for big stock. Un- 

 natural and rapid burning of heather and a wholly artificial state of Grouse 

 farming; also interbreeding." 



In the above quotations, which are perfectly sound so far as they go, we have 

 a very fair summary of possible predisposing causes ; but the immediate cause 

 of " Grouse Disease," whether we consider the disease to be pneumonia, or 

 Strongylosis, or Coccidiosis, or Enteritis, or any other sickness in the world, 

 is not touched. 



The primary or acting cause of Klein's acute infectious pneumonia was 

 believed to be a sub-species of the Bacillus coli ; the primary cause of Cobbold's 

 Strongylosis is the nematode worm Trichostrongylus pergracilis ; the primary 

 cause of Grouse Coccidiosis is Eimeria (coccidium) avium, and so on ; not 

 east winds or the absence of the Peregrine Falcon. 



Until we have discovered the active agent in a disease we cannot say that we 

 know its cause. This is a fundamental rule, and to be satisfied with predisposing 

 causes is to be satisfied with less than half the truth, though that half is, of 

 course, very important if our intention is to proceed further in the attempt 

 to discover a remedy for the disease in question. 



The consequences of what has appeared to be epidemic disease amongst 

 Grouse have been so disastrous from time to time in the past that 

 Alimor- it is not surprising to find a very widespread tendency amongst 

 Grouse* 1 sportsmen and gamekeepers to attribute every death and every case 

 "Grouse of sickness on the moor to the so-called " Grouse Disease." 



It is obvious that Red Grouse, in common with other birds, may 

 be subject to more than one form of disease ; but when a certain form of 



