The Role of Habits 149 



and a hundred other examples could be given. But 

 what we do not know is that the induced blindness of 

 the goldfishes has any effect on their offspring reared 

 from eggs developed in the light. And it is at present 

 illegitimate to say, except as a working hypothesis, 

 that the blindness of certain cave fishes and sala- 

 manders is due to generations of darkness and disuse 

 of eyes. Yet our impression is that increase of knowl- 

 edge will lead us to discover that the experience of the 

 individual may count as a factor in evolution by 

 some entailment on the offspring. In other words, we 

 are unwilling to foreclose the question as to possible 

 transmission of at least some specific representation 

 of an individually acquired modification. It is ad- 

 mitted by all that the individual experience may give 

 the individual opportunities to play its new heredi- 

 tary cards. But is there nothing more? 



§17. Habits and the Possible Entailment of Their 



Results. 



From everyday experience and from convincing ex- 

 periments it is certain that the organism, especially 

 when young, is modified by peculiarities of "nurture" 

 — habitudinal, nutritional, and environmental. It 

 runs the gauntlet of a successsion of influences which 

 produce "dints" or "modifications." A modification 

 may be defined as a bodily change induced in the 

 individual's lifetime as the direct result of some 

 peculiarity in habits, nutrition, and environment, 

 and so transcending the limits of organic elasticity 

 that it persists after the inducing conditions have 



