THE LIVING MACHINE BUILDING FACTORS. 155 



have identical properties with the egg of the first 

 generation. Hence if one of these new eggs de- 

 velops into an adult it will produce an adult ex- 

 actly like the second generation, since it contains 

 chromosomes which are absolutely identical with 

 those from which the second generation sprung. 

 There is thus no difficulty in understanding why 

 the second generation will be like the first, and 

 since the process is simply repeated again in the 

 next reproduction, the third generation will be 

 like the second, and so on, generation after gen- 

 eration. A study of the accompanying diagram 

 will make this clear. 



In other words, we have here a simple under- 

 standing of at least some of the features of hered- 

 ity. This explanation is that some of the chro- 

 matin material or germ plasm is handed down 

 from one generation to another, and is stored 

 temporarily in the nucleii of the reproductive 

 cells. During the life of the individual this germ 

 plasm is capable of increasing in amount without 

 changing its nature, and it thus continues to grow 

 and is handed down from generation to genera- 

 tion, always endowed with the power of develop- 

 ing into a new individual under proper conditions, 

 and of course when it does thus give rise to new 

 individuals they will all be alike. We can thus 

 easily understand why a child is like its parent. 

 It is not because the child can inherit directly 

 from its parent, but rather because both child 

 and parent have come from the unfolding of two 

 bits of the same germ plasm. This fact of the 

 transmission of the hereditary substance from 

 generation to generation is known as the theory 

 of the continuity of germ plasm. 



Such appears to be, at least in part, the ma- 



