THORNLESS BLACKBERRY 215 



clusively, owing to the dominance of the factor 

 for thorns. But if a few berries or individual 

 drupelets of a berry had been fertilized with 

 pollen from a flower of the thornless plant itself, 

 these would (according to a formula with which 

 we are already familiar) stand one chance in four 

 of combining recessive factors and thus of pro- 

 ducing thornless progeny. 



And of course from then onward the case pre- 

 sented no difficulty as far as this character was 

 concerned. We must now be at hand to make 

 sure that the thornless flowers were fertilized 

 solely with pollen of their own sort. This, of 

 course, could bring together only recessive fac- 

 tors, that is to say, factors for thornlessness, and 

 the result could not be in doubt. The thorn- 

 producing factor would be left entirely out of 

 the composition of bushes sprung from such a 

 union, and they would inevitably be thornless. 



THORNLESS, BUT LACKING QUALITY 



But while the production of a thornless race 

 of dewberries was thus accomplished with com- 

 parative ease, it must be understood that this was 

 really only the beginning of the task. 



The original berries from which the thornless 

 vines were grown were of no commercial value. 

 They were small and of very indifferent flavor. 



