ANATOMY AND PHYSIOLOGY OF RED GROUSE 181 



more comparatively strong and healthy, but not so well pre- 

 pared to meet the critical conditions of early spring as those 

 included in the first class. These, probably, of the second 

 class are the birds that form the first class in the following 

 year, or perhaps they cannot even rise to that, and fall victims 

 to the spring mortality. 



