1 8 National Life 



like producing like, we shall find, as I have 

 recently done, that the same laws are probably 

 true for the mushroom and for the forest 

 tree ; that the principle of heredity runs with 

 certainly no weakened intensity from the 

 lowest to the highest organisms, and from 

 their least to their most important characters. 

 Now, let us try to understand exactly what 

 this means. Of a definite child of A and B 

 we can assert nothing with certainty, but of 

 all the children of a definite class of parents 

 like A and B we can assert that a definite 

 proportion will have a definite amount of 

 any character of A and B with a certainty as 

 great as that of any scientific prediction what- 

 ever. I am not speaking from belief or from 

 theory, but simply from facts, from thousands 

 of instances recorded by my fellow-workers 

 or myself. Here is a great principle of life, 

 something apparently controlling all life from 

 its simplest to its most complex forms, and 

 yet, though we too often see its relentless 

 effects, we go on hQgjng that at any rate we 

 and our offspring shall be the exceptions to 

 its rules. For one of us as an individual 

 this may be true, but f^ the average of us 



