162 The Unity of the Organism 



We must now point out specifically what appeared only 

 incidentally in the previous discussion, namely, that the 

 integrative action of hormones and of the nervous system 

 are to a considerable extent the reverse of each other as 

 regards their relation to development and to adult func- 

 tion. That is, while harmones are, perhaps, more impor- 

 tant in development and become relatively less significant 

 with the advancing age of the individual, the nervous sys- 

 tem plays a minor part in integrating the developmental 

 processes but becomes of supreme importance in this way 

 for the functioning of the adult. Or, stating the generali- 

 zation in another way, integration of the organism is ac- 

 complished by chemical means chiefly, and by neural means 

 little or not at all, during early life, and by neural means 

 chiefly and by chemical means secondarily in later life. 



One can hardly fail to see, in a general way, the bearing 

 of this on the familiar truth that the life of the individual 

 among the higher animals, man especially, is successively 

 vegetal, animal, emotional, and finally rational and intel- 

 lectual in its dominant characteristics, with the successive 

 stages of earlier and later childhood, youth, and earlier 

 and later maturity. 



The Author's Indebtedness to Sherrington's Work 



My dependence upon Sherrington's work in this field will 

 be so great as to make it impossible to acknowledge it at 

 every point. I therefore make at the outset the general 

 statement that a large part of my discussion consists of a 

 re-wording and rearranging of facts and ideas contained in 

 this physiologist's important book, The Integrative Action 

 of the Nervous System. But while my chief reliance here 

 is on Sherrington's work, the writings of Cannon and his 

 collaborators have been the most important source of what 

 I have to say about the autonomic nervous system. Can- 



