DARWINISM AND HEREDITY. 



35 

 them 





and importance in evolution we must analyse 

 further in the light of heredity. 



When the characters of the parent reappear in the off- 

 spring we say in popular language that they are inherited. 

 There is a mechanistic aspect of heredity just as there is 

 of life. Why, we may ask, do the reproductive egg-cells 

 of a snail, a fly, and a fish, all under the same conditions, 

 and bathed by the same water, reproduce the same 

 bodily structure, the same functional capacities, the same 



Frequency of different lengths of beans measured by 

 De Vries. 



Frequency of different types of beech leaves measured by 

 K. Pearson. 



psychological powers, the same complex kind of individu- 

 ality as each of the parent forms ] The answer is that 

 they are formed of the same protoplasm as the parent ; 

 they are chips of the old block. Both parent and off- 

 spring develop from the same starting-point ; a particu- 

 lar mixture of substances, having a peculiar intimate 

 architecture, or specific structure, and undergoing a 

 particular kind of metabolic change. Under approxi- 

 mately similar conditions they are bound to develop into 

 approximately similar organisms. This particular kind 



