138 DEVELOPMENT AND HEREDITY. 



each generation will present new characteristics to 

 be acted upon by the forces of environment. Thus, 

 though the environment remain the same, the simple 

 continuance of a race is continually bringing that 

 race into new relations with the forces of nature. 

 This developing action of the environment is some- 

 what modified by death and the process of reproduc- 

 tion. The same relation of force and matter is 

 necessary each time to produce successively the 

 same result, and so if any generation is to resemble 

 the one preceding, it must pass through the same 

 course of growth. When the first living organism 

 had attained its maturity, and part of it had sepa- 

 rated off to form a new generation, the second 

 organism could only come to resemble the first by 

 possessing the capacity of responding in the same 

 way to the stimuli of environment. Thus it would 

 pass through the same process of growth, and when 

 it had reached a development equal to that of its 

 parent, it would nevertheless be different, for it 

 would be composed of living matter which had twice 

 passed through the same round of activities. The 

 same would be true for the third and each succeeding 

 generation. But this added complexity of co-ordina- 

 tions, or fixity of associations, would be apparent as 

 such only when each generation reached a point of 

 growth equal to that of its parents at their maturity. 



