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 cecum 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. 
* This view was stongly forced upon my mind during some 
observations made on a Wapiti deer (Cervis canadensis) at the 
Zoological Gardens. In the course of three or four months this 
