VESTIGIAL PARTS. 69 



This is merely set forth as an example of the process,, 

 and it may be illustrated by reference to parts far less, 

 vital than the intestines, viz., the antlers of deer. 



The antlers when young and growing are covered 

 with a vascular membrane, the " velvet," which bears the 

 same relation to the antlers as periosteum bears to 

 bone. As long as the antlers retain the velvet they live 

 and increase in length and thickness. After a time the 

 velvet thins, sloughs, and gradually falls from the bony 

 portion of the antlers, which gradually dies, and, being 

 devoid of sensation at this stage, constitutes powerful 

 weapons of offence or defence. In time the nutrition 

 fails in them also, and at length the dead antlers fall. 

 The phenomenon may be explained thus : the antlers 

 are supplied at a great disadvantage, for the blood has to 

 travel a long distance to reach them, and is unassisted 

 by any neighbouring anastomosing vessels such as we 

 find in other parts of the body ; consequently every inch 

 added to the antler increases the difficulty of supply and 

 makes its life more precarious ; finally the length of the 

 antler exceeds the distributing power of the heart, 

 nutrition fails, the velvet is shed, and the bony tissue 

 of the antler dies and falls. We have here conditions 

 analogous to the caecum of the rhinoceros, and few can 

 doubt that those enormous antlers which decorated the 

 head of Megaceros hibernicus have played a part in 

 bringing about its failure in the great struggle of life 

 perpetually raging in the organic world. 1 



1 This view was stongly forced upon my mind during some 

 observations made on a Wapiti deer (Cervus canadensis) at the 

 Zoological Gardens. In the course of three or four months this 



