THEORIES IN PRACTICE 375 



transmission, showing the phenomena of domi- 

 nance and reeessiveness, 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 individual 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 

 it is with their manipulation that he is chiefly 

 concerned. Their relative insignificance is evi- 

 denced in the fact that the plant developer can- 

 not possibly produce major modifications in the 

 organisms with which he deals. 



He does not attempt to make squash vines 

 into oak trees, or blackberry vines into tomatoes. 



He recombines those newer, and hence less 

 important, structures and qualities of which the 

 fact of their Mendelizing is adequate proof of 

 their newness and relative unimportance. If he 

 would get beyond this and create really new 

 forms, adding something to the plant that no an- 

 cestor of the plant ever had, he could hope to do 

 this only if a term of life were granted him that 



