96 BIOLOGY AND SOCIAL PROBLEMS 



forms of inheritance remain unanalyzable from 

 the Mendelian standpoint, we may conclude 

 that this explanation does not exhaust the 

 field of heredity. But even if Mendelism is an 

 explanation of only a part of the phenomena 

 of heredity, it represents an advance in all 

 respects the most important that the science 

 of genetics has yet made, and it opens up a 

 prospect to the experimentalist which is no 

 less alluring than it is full of promise. 



Notwithstanding the fragmentary character 

 of our knowledge of reproduction, we know 

 that a child takes after its parents because the 

 fertilized egg from which it has grown is made 

 up of living material part of which came from 

 each immediate ancestor. The amount of all 

 the material in the egg is immensely small 

 compared with that of the person who devel- 

 ops from it, and the amount of that material 

 in the egg concerned with heredity is probably 

 not over a thousandth part of the whole egg ; 

 nevertheless this infinitely minute quantity of 

 material, rather than the environment, stamps 

 upon us with an iron hand the configuration 

 of our early life, a configuration which is so 

 rigidly determined that where two or more 

 individuals come from the same egg almost 



