THE CHANGES OF PLUMAGE IN RED GROUSE 51 



about eight cocks to every hen in April and in May), may have 

 caused the alteration in the season of the moult, simply because 

 the vis vitce of the cock bird, insufficient as we now know it to be 

 at the close of winter for the ordinary calls of reproduction, 

 would be still more disastrously insufficient if preceded by an 

 early moult. 



At the present time the cock undoubtedly breeds in the old 

 winter plumage, without any acquisition of a new breeding 

 plumage, and, as has recently been pointed out by Mr Ogilvie- 

 Grant, what have been regarded by Mr Millais as new " spring 

 feathers " on the neck are in fact the old autumn feathers, 

 which on that part of the body do not become worn and 

 faded. 



It is unlikely that any feather of the Grouse is altered 

 in pattern, tone, or any other character, when once it has 

 completed growth and has been cut off from the circulation, 

 for once the circulation has ceased beyond the entrance to the 

 base of the shaft, and once the feather is cut off from the 

 circulation in the deeper living layer of the skin, it is no more 

 likely or able to change the pigment which is responsible for 

 its pattern or its colour than would be the same feather had it 

 been plucked out and kept entirely separate from the bird. 



If there are, as has been held, distinct pigments, such, 

 for example, as buff, black, and orange-red, in the various 

 colour tones of the Red Grouse, it becomes easier to see that the 

 loss of the red pigment, which is utilised for the eggs, leaves the 

 buff and the black in greater quantity for the nesting season 

 plumage. In the winter all three would once more be available. 



The whole question of pigment production arjd pigment 

 distribution, intimately connected as it is with the question of 

 the excretion of waste products and the deposition of fat, both 

 in health and in disease, has not reached a stage which admits 

 of dogmatic statement upon the subject of pattern change 

 in feathers without moult. 



That the cock bird should moult the feathers of the legs 

 and feet between March 30th and June 17th is no longer difficult 



