140 DEVELOPMENT AND HEREDITY. 



round of responses, — that is, has attained matu- 

 rity, — it then stands in a new relation to its envi- 

 ronment through the changed state of its nervous 

 system, therefore we should expect any change 

 of growth, any variation new to the race, to follow 

 at or near the period of maturity. As is well 

 known, this is what really occurs in nature ; the 

 newest variations in the race are the last to 

 appear in the growth of the individual, the 

 specific differences appear later than generic differ- 

 ences, and these latter later than class differences. 

 Remembering that growth, development, and repro- 

 duction are merely forms of organic action, and 

 under the control of nervous force, we must believe 

 that they are subject to the fundamental laws that 

 control nervous action in general, as we discern 

 those laws in the involuntary movements of our 

 bodies and in the working of our minds. Now 

 it is a familiar fact that repetition increases facil- 

 ity and rapidity of action, and thus we observe 

 that the frequent repetition of the processes of 

 growth and development have rendered it possible 

 for the brief life of an individual to encompass 

 the development which the race has been untold 

 ages in acquiring. We find the proofs abundant 

 in nature that new characteristics of animals tend 

 to appear earlier and earlier in each subsequent 



