LECTURE XXVII 



INCONSTANCY OF IMPROVED RACES 



The greater advantages of the asexual multi- 

 plication of extremes are of course restricted to 

 perennial and woody plants. Annual and bi- 

 ennial species cannot as a rule, be propagated 

 in this way, and even with some perennials hor- 

 ticulturists prefer the sale of seeds to that of 

 roots and bulbs. In all these cases it is clear 

 that the exclusion of the individual variability, 

 which was shown to be an important point in 

 the last lecture, must be sacrificed. 



Seed-propagation is subject to individual as 

 well as to fluctuating variability. The first 

 could perhaps be designated by another term, 

 embryonic variability, since it indicates the 

 fluctuations occurring during the period of 

 development of the germ. This period begins 

 with the fusion of the male and female elements 

 and is largely dependent upon the vigor of these 

 cells at the moment, and on the varying qualities 

 they may have acquired. It comprises in the 

 main the time of the ripening of the seed, and 



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