Theory of Antlers 177 



that a bodily character arising intrinsically in the 

 germ plasm, and expressed as a mutation, should 

 come secondarily under the influence of the gonadial 

 hormones, so that it is not activated in development 

 without that stimulus. 



The antlers of stags are traced back by Mr. Cun- 

 ningham to the butting habit, which stimulates an 

 upgrowth from the frontal bone; the increased 

 growth results in products which act as a hormone on 

 the germ-cells, stimulating and affecting the germinal 

 "factors" for the frontal bone and adjacent tissues. 

 So, as generations pass, the outgrowth from the 

 frontal bone becomes stronger and stronger. There 

 is a centripetal hormone action from the exaggerated 

 antler-tissue to the corresponding factor in the germ- 

 cells, and there is a centrifugal hormone action from 

 the male reproductive organ to the tissues associated 

 with the growth of the antler. This is desperately in- 

 genious, but is it not in the air? In the same way the 

 primary origin of the milk glands is found in the 

 mechanical stimulus of sucking ; centripetal hormone 

 action accounts for their hereditary entailment ; cen- 

 trifugal hormone action accounts for their appro- 

 priate development in the individual mammalian 

 mother. But do we know anything definite in regard 

 to hormones formed by modified tissues ? Are we even 

 sure that they exist? If we venture to suppose that 

 there really is an occasional transmission of indi- 

 vidually acquired bodily modifications, Mr. Cunning- 

 ham offers an ingenious theory of the way in which 

 the hereditary entailment might come about. But is 



