ON THE QUICK GROWING WALNUT 



edity and evolution, that all modified characters 

 that effect the constitution of the individual are 

 heritable. Even the slightest modification of 

 structure due to altered nutrition, to changed tem- 

 perature, or the like, probably makes its influence 

 felt on the next generation in exact proportion to 

 its value in the great complex scheme of charac- 

 ters with which it is associated. 



But this statement must not be misinterpreted. 

 It must not be supposed that any minor modifica- 

 tion of an individual can influence, except in an 

 infinitesimal way, the inheritance of the offspring 

 of that individual. 



For the new modification will be, in the nature 

 of the case, only as an alien drop or two in an 

 ocean of hereditary tendencies. 



Or, stated in somewhat more modern terms, 

 the hereditary factor that represents the new mod- 

 ification will be as one minor factor among thou- 

 sands or perhaps millions of pre-existing factors. 



If we revert to an earlier illustration, in which 

 we thought of the germinal nucleus as a piece of 

 architecture made up of multitudes of factors of 

 heredity, we may think of the new factor as one 

 added brick in a structure of palatial proportions, 

 made up of thousands of bricks. 



Yet it is by the cumulative effect of such minor 

 modifications, we may well believe, that evolution 



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