82 SEXUAL DIMORPHISM 



partly to the scarcity of food. The sanibar at Woburn 

 Abbey La stated to shed its antlers every year, and the ex- 

 perience of surgeons proves that absorption naturally follows 

 on the death of a portion of bone. 



We have next to consider whether the growth of the new 

 antler after the old was shed was originally a spontaneous 

 process of recrescence, like that of the arm of a star-fish 

 after amputation, or whether it was dependent on renewed 

 irritation. It is certain that if the growth did not occur 

 spontaneously, the irritation would be renewed at the next 

 rutting season, and the previous course of growth and 

 shedding of the antler would be brought about again. If, on 

 the other hand, the growth always took place as it does now, 

 before the rutting season, and without any external irritation, 

 it is difficult to see any reason for the increased development in 

 successive years. It seems most reasonable to suppose that in 

 the early stages of the evolution, after one pair of antlers had 

 been shed, the growth of the succeeding pair was stimulated by 

 irritations of the periosteum before the growth was completed. 



This view seems also to be required to explain the 

 branching of the antler, which when first developed is a 

 single spike. Darwin remarks that although the antlers are 

 efficient weapons, there can, he thinks, be no doubt that a 

 single point would have been much more dangerous than a 

 branched antler. He thinks that they do not appear perfectly 

 well adapted as a means of defence against rival stags, as 

 they are liable to become interlocked, and he thinks that 

 they may serve in part as ornaments. But we have no 

 evidence that the female deer has any choice but to accept 

 the victorious stag, except that she occasionally pairs with an 

 unoccupied stag while her original lord is engaged in combat. 

 I think, therefore, the branching must have been originally 

 caused by irritation of the periosteum before the velvet was 

 shed. 



