CHAPTER XX 



HEREDITY 



I. The Facts of Heredity 2. Theories of Heredity : theological, 

 metaphysical, mystical, and the hypothesis of pangenesis 

 3. The Modern Theory of Heredity 4. The Inheritance of 

 Acquired Characters 5. Social and Ethical Aspects 6. Social 

 Inheritance 



WE have spoken of the three Fates which were believed to 

 determine of what sort a life should be. With the decay 

 of poetic feeling, and in the light of common science, the 

 forms of the three sisters have faded. But they are realities 

 still, for men are thinking more and more vividly about the 

 factors of life, which to some are " powerful principles," 

 to others living and personal, to others unnameable. 

 Biologists speak of them as Heredity, Function, and En- 

 vironment : the capital with which a life begins, the 

 interest accruing from the investment of this in varied vital 

 activities, and the force of circumstances. But while it is 

 useful to think of Heredity, Function, and Environment as 

 the three fates, we must not mystify matters by talking as 

 if these were entities acting upon the organism. They 

 are simply aspects of the fact that the animal is born and 

 lives. The inheritance is the organism itself, and heredity 

 is only a name for the relation between successive genera- 

 tions. Moreover, the function of an organism depends 

 upon the nature of the organism, and so does its suscep- 

 tibility to influences from without, 



I would at present define heredity as the organic relation 



