380 LUTHER BURBANK 



minor factors, so that the total number of heredi- 

 tary factors stored in the germ plasm and seek- 

 ing for recognition, in the case of a single plant, 

 is a round million. 



Each of these million factors has been devel- 

 oped in the long slow process of evolution, one 

 after another added, generation by generation, 

 or era by era, beginning with the time when the 

 remote primordial progenitor of the plant was 

 a single-cell organism. 



In the course of the ages, development has 

 taken place along diverse lines, and it has come 

 to pass that certain combinations of hereditary 

 factors have been grouped into systems that 

 have so long been working in harmony together 

 that they cannot be separated. The members of 

 one such group determine the architecture of the 

 root; the members of another group determine 

 the architecture of the stem; and so on for each 

 of the patent characters. 



But there are other groups of factors that are 

 less ancient in their origin. There were some 

 that made their way into the germ plasm of the 

 ancestors of the plant so recently as half a mil- 

 lion years ago. There are others that are mere 

 parvenus of perhaps ten thousand years. And 

 there are yet others that are upstarts of literal 

 yesterday. 



