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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