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The variety containing the four recessives would give 

 the lowest yield of all, and any of the varieties containing 

 one of the dominants would give a higher yield. The 

 crossing of one of the varieties containing one dominant 

 with the lowest yielding variety would yield no higher 

 yielding variety, but, if two of the varieties, one with 

 one and another with a second dominant, were crossed, 

 the hybrid would yield more than either parent, and, 

 by retaining and purifying the highest yielding group 

 in the hybrid's progeny and eliminating the other three, 

 a new higher yielding variety could be produced. Simi- 

 larly, by mating a variety containing two of the domi- 

 nants with another containing one, a still higher 

 yielding variety could be obtained, and finally, by 

 crossing two groups which contain all the dominants 

 between them, the highest yielding variety of all could 

 be obtained. The chances of getting higher yielding 

 progeny are greatest when the parents are themselves 



