40 THE INFLUENCE OF ENVIRONMENT, ETC. 



d the apples. The combination ab is a remarkably 

 unstable one in the presence of cd, and the affinity 

 between a and d is very great ; an interchange 

 takes place as follows : 



ab -f cd = ad + be. 



These examples are no doubt somewhat crude, yet 

 they will serve to indicate that if we could define 

 all the conditions we should be able to draw up an 

 equation for a man's life and show how, given the 

 man and the conditions acting on him, there was 

 but one path open to him. 



In conclusion let me refer to a statement by 

 Herbert Spencer in which he discusses the influence 

 of environment on animals ; starting, however, 

 from a standpoint that I cannot accept, viz., the 

 Lamarckian hypothesis of animals responding by 

 efforts of their own to changes in environment. 



The more complete the correspondence between 

 external and internal changes, the more complete 

 the power of response to changes of environment, 

 the higher is the grade of the animal and, as a rule, 

 the longer is its life and the less its fertility. In 

 this respect man stands the highest, for instance, in 

 the power of counterbalancing changes of tempera- 

 ture, and in the supply of food consequent on 

 seasons. 



Perfect correspondence to change in environ- 

 ment would be perfect life, eternal existence. 

 Death, whether from natural decay, disease or 

 accident, is simply due to failure of the organism to 

 respond effectively to changes of environment. 



