ON THE QUICK GROWING WALNUT 



compete with the dominant character. And 

 whether in the end the new dominant character 

 will prove itself and prevail, or whether the re- 

 cessive character will re-establish itself, depends 

 entirely on the value for the species of one char- 

 acter as against the other. 



Mendelian heredity, then, is a testing out 

 process for new characters. It is, as it were, the 

 skirmish-line of the advance guard of evolution. 

 So long as a character is subject to Mendelian 

 transmission, showing the phenomena of domi- 

 nance and recessiveness, it is a relatively new and 

 unfixed character still on trial. 



And in proportion as any character has proved 

 itself and has passed the trial stage, it becomes 

 blended with the hereditary factors that have more 

 stable position, just as conscious acts of the indi- 

 vidual become instinctive or reflex when often 

 enough repeated. 



In this view, then, the so-called unit characters 

 that Mendelize are, as was said before, merely the 

 fringe to the great fabric of heredity. They serve 

 the plant developer an admirable purpose, and, 

 indeed, it is with their manipulation that he is 

 chiefly concerned. Their relative insignificance is 

 evidenced in the fact that the plant developer 

 cannot possibly produce major modifications in 

 the organisms with which he deals. 



