498 THE INDIVIDUAL AND THE RACE: 



power of the higher nature to modify what has undergone 

 automatisation or enregistration, the greater the capacity 

 of selecting and altering the environment. We do not know 

 all the evil that is in our inheritance, therefore we should 

 not take too many risky chances. We do not know all the 

 good that is in our inheritance, therefore we should give 

 it every chance. Biology and history, as well as our con- 

 science, give the lie to the mechanistic fatalism which asserts 

 that we have not, in any measure, freedom of self-develop- 

 ment. 



§ 7. Heredity and Personality. 



The greatest advance in the modern study of heredity has 

 been the disclosure of unit-characters or Mendelian charac- 

 ters. It is certain that there are numerous hereditary char- 

 acters which behave in a distinctive and independent way 

 in inheritance, being distributed as indivisible entities accord- 

 ing to a definite scheme. They are clear-cut, either there 

 or not there ; they do not blend or intergrade ; and they 

 are infallibly present in a certain proportion of the offspring. 

 They seem to be represented in the germ-cells by definite 

 determinants, factors, or genes, the nature of which is un- 

 known. Some have likened them to ferments;, others to 

 differences in the ultra-microscopic architecture. It is quite 

 likely that several factors may be concerned in one character, 

 or that one factor may influence more than one character. 

 The gist of the Mendelian discovery is, in Pearl's words, 

 this: ^^ Hereditary differences behave, in the main, as discrete 

 units, which are shuffled about and re-distributed to individ- 

 uals in the course of the hereditary process, to a considerable 

 extent independently of each other ; and in typical cases this 

 re-distribution follows the simplest of statistical laws of 



