292 ZOOLOGY. 



it, and also that dead bone is absorbed by the adjacent 

 living tissue. Therefore the stripping of the velvet is the 

 real cause of the shedding of the antler. It was formerly 

 supposed that the formation of the burr caused the death 

 of the antler by constricting and closing the arteries that 

 entered from the bone below; but the bone within the 

 antler is alive and blood circulates in it after the burr 

 is formed : it dies gradually. When it is dead the living 

 bone below the burr absorbs the layer of bone next to it 

 and the antler necessarily drops off, the separation taking 

 place below the burr, not above it. 



It is true that the growth of the antler and the stripping 

 of the velvet do not actually follow, but precede the 

 fighting of the stags, but on the other hand it is difficult 

 to believe that processes so similar to natural physiological 

 processes could have arisen by "mutations," which were 

 not caused by the fighting of the stags. If the mutation 

 was independent of the habits of the animal it is impossible 

 to understand how the habits and the development of the 

 antlers should correspond so closely. If the fighting of 

 the stags caused the original growth, and then the stripping 

 of the skin, which was followed by the shedding of the 

 antler, we could understand that in course of ages the 

 development might gradually take place earlier in the 

 year until the present state of things was brought about. 



17. Effects of Castration. It is held by many, how- 

 ever, that there is no evidence of the heredity of such 

 modifications, and until recently it was maintained that 

 there was no means by which a change in a part of the 

 soma could affect the gametocytes. It is true that muti- 

 lations are not inherited even when repeated for countless 

 generations, as in the docking of lambs' tails, but this 

 does not prove that physiological changes such as increased 

 growth or "hypertrophy" may not be inherited, and an 

 infinitesimal inheritance in one generation may become 

 complete inheritance in time. 



The view that the development of all parts of the body 

 is due to the properties of the ovum alone is contradicted 

 by the recently discovered facts concerning internal secre- 



