ANATOMY AND PHYSIOLOGY OF RED GROUSE 179 



whereas in winter they are generally small and black and 

 deeply pigmented. 



Occasionally a very emaciated cock bird will be found with 

 testes only half the normal size during the breeding season ; 

 but, as a rule, the effect of disease on the development of the 

 hen's generative system, both ovary and oviduct, is far more 

 noticeable than is the case in the male. 



It is very noticeable that in sick Grouse hens there is no 

 development of the ovaries or enlargement of the oviduct and 

 cloaca such as takes place in spring in every healthy hen. 

 The ovaries remain small and undeveloped as in midwinter. 

 Such birds are barren if they pair, for as a rule they cannot 

 lay an egg, but they pair nevertheless, as every gamekeeper 

 knows to his cost. 



This difference between the male and the female Grouse is 

 significant. It seems that, in the male, appearance may be 

 sacrificed to efficiency, for in cases of disease the generative organs 

 may be fully developed while the plumage is backward ; whereas 

 in the female, appearance comes first, and the nuptial plumage 

 is donned at any cost, often to the undoing of the hen herself, at 

 any rate to the complete undoing of her power to produce an 



egg. 



There are, of course, many sickly hens that not only don 

 the breeding dress but also lay a modicum of eggs. They 

 appear later in the shooting season with every sign of disease 

 and exhaustion upon them, but yet recovering. 



Grouse that have survived the mortality of April and 

 May do not usually die later in the year. They become con- 

 valescent through the summer and autumn, owing to good food 

 and better weather. There is, in fact, no autumnal outbreak of 

 disease ; but there is an increased opportunity for the collec- 

 tion of birds that have been sick and are convalescent. These 

 birds can fly, and are shot in August and September ; it is 

 only when they are discovered in the bag, in the process of 

 inspection later in the day, that they are suspected of disease, 

 and are forwarded to the laboratory for examination. 



