280 REPORTS ON THE STATE OF SCIENCE. 



take place. THen, even if there is no further acceleration of the actual 

 rate of growth after the controlling influence has once been completely 

 removed, the lengthening life-history will still afford opportunities for 

 increase of size. It seems not impossible, however, that acceleration 

 might also continue in connection with the shortening up of the stages 

 of development in the ontogeny. 



I should like to meet in advance another objection which may be 

 raised to the views herein advocated. It may be urged that many of 

 the bizarre and almost monstrous characters under discussion, such, for 

 example, as some of the excrescences of the dermal armature in extinct 

 reptiles, can never have had any value as adaptations, and that there- 

 fore natural selection could never have encouraged them to increase so 

 much in size as to get beyond her control. Here, however, the principle 

 of correlation comes in. Just as many different parts of the body are 

 affected by disease of the pituitary gland, so the removal of the gland 

 which controlled the development of some undoubtedly useful organ. 

 Huch as a frontal horn, might at the same time permit the growth of all 

 sorts of excrescences which have no adaptive significance. . 



I need hardly say that I have no wish to speak dogmatically with 

 regard to the cause of that remarkable momentum which organisms 

 certainly seem in many cases to acquire during the course of their evo- 

 lution. Our knowledge of internal secretions and their specific action 

 upon the different parts of the body is still in its infancy, indeed it has 

 hardly commenced, but I venture to point out to biologists a possible 

 clue to what has been for a long time an insoluble enigma. I hope that 

 my suggestion will be freely criticised and that it may give rise to a 

 discussion from which some grain of truth will ultimately emerge. 



