MATERIALS OF HEREDITY 5 



The Materials of Heredity 



How does it happen that different individuals are at the 

 beginning composed of different materials? The different 

 materials of different individuals are received from their 

 parents. The fact that the materials so received differ in 

 different cases is a consequence of certain relations which 

 may be summarized in a preliminary way as follows (de- 

 tails are taken up later) : 



The parents contain in their cells a large stock of ma- 

 terials of many kinds, with diverse physiological effects; 

 these are in the form of minute particles. Each parent 

 contributes to the child but half of his stock of materials, 

 the other parent contributing the other half. And the half 

 which each parent contributes is taken in a random way, 

 later to be described In full. There is a system of dis- 

 tributing these materials, a system that much resembles the 

 operation of a lottery, so that any child receives a different 

 set of materials from every other. 



Just how that lottery turns out for any given Individual 

 is perhaps the most important matter of his life. For It 

 Is through this system of distribution that each receives his 

 particular endowment, the things on which depend his In- 

 dividuality and his abilities. It Is the method by which each 

 receives the capital on which he is to do business for the 

 rest of his life. On the way this distribution of materials 

 from the parents takes place depend more than on any 

 other one thing the individual's personality, powers, for- 

 tune and fate. The distribution occurs In accordance with 

 certain rules, and It Is these rules that are the foundation 

 of what are called the laws of heredity. 



To understand the nature of human beings or other 

 organisms; to understand their likenesses and differences, 

 to understand how later generations are related to earlier 

 ones, the first requisite is to understand these materials and 



