174 THE STORY OF LIFE'S MECHANISM. 



HEREDITY. 



The offspring which arise by these processes 

 of division are like each other, and like the 

 parent from which they sprung. This is the 

 essence of what is called heredity. Its signifi- 

 cance in the process of machine building is evi- 

 dent at once. It is the conserving force which 

 preserves the forms already produced and makes 

 it possible for each generation to build upon the 

 structures of the earlier ones. Without it each 

 generation would have to begin anew at the 

 beginning, and nothing could be accomplished. 

 But since this principle brings each individual to 

 the same place where its parents stand, and thus 

 always builds the offspring into a machine like 

 the parent, it makes it possible for the successive 

 generations to advance. Heredity is thus like the 

 power of memory, or better still, like the inven- 

 tion of printing in the development of civilization. 

 It is a record of past achievements. By means 

 of printing each age is enabled to benefit by the 

 discoveries of the previous age, and without it the 

 development of civilization would be impossible. 

 In the same way heredity enables each generation 

 to benefit by the achievements of its ancestors 

 in the process of machine building, and thus to 

 devote its own energies to advancement. 



The fact of heredity is patent enough. It has 

 been always clearly recognized that the child has 

 the characters of its parents, and this belief is so 

 well attested as to need no proof. It is still 

 a question as to just what characters may be 

 inherited, and what influences may affect the 



