ON THE QUICK GROWING WALNUT 



perimenters who have paid attention only to a few 

 conspicuous characters that Mendelize, that all 

 possible combinations of characters will occur 

 among the second generation hybrids, provided 

 only enough of these are produced. 



Possibly this statement is correct. But it is not 

 susceptible of demonstration because it would not 

 be feasible to produce enough individuals in a 

 single generation to put it to the test. For the num- 

 ber of possible combinations increases in geo- 

 metrical ratio, as we have seen, with the increased 

 number of characters under consideration. And a 

 really penetrating view of the situation reveals to 

 us hereditary factors in the germ-plasm of each 

 individual plant that would be numbered, could 

 we isolate them, not merely by tens or scores; not 

 merely by hundreds or thousands; but rather by 

 hundreds of thousands or millions. 



Such a statement probably will not surprise any 

 one who has read the various preceding chapters 

 in which we have viewed various aspects of her- 

 edity. But to those experimenters who have been 

 prone to think of "unit characters" as few in num- 

 ber, such a statement will perhaps seem anoma- 

 lous. Yet there can be no question that it is fully 

 justified. 



In point of fact, what the present day student 

 of heredity usually speaks of as a unit character 



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