746 Fluctuations 



fluenced to a noticeable degree before this union. 

 This is the period of the determination of indi- 

 vidual variability. As soon as ramifications be- 

 gin, the external conditions act separately on 

 every part, influencing some to a greater and 

 others to a lesser degree. Here we have the 

 beginning of partial variability. At the outset 

 all parts may be affected in the same way and 

 in the same measure, but the chances of such an 

 agreement, of course, rapidly diminish. This is 

 partly due to differences in exposure, but main- 

 ly to alterations of the sensibility of the organs 

 themselves. 



It is difficult to gain a clear conception of the 

 contrast between individual and partial varia- 

 bility, and neither is it easy to appreciate 

 their cooperation rightly. Perhaps the best 

 way is to consider their activity as a gradual 

 narrowing of possibilities. At the outset the 

 plant may develop its qualities in any measure, 

 nothing being as yet fixed. Gradually how- 

 ever, the development takes a definite direction, 

 for better or for worse. Is a direction once 

 taken, then it becomes the average, around 

 which the remaining possibilities are grouped. 

 The plant or the organ goes on in this way, un- 

 til finally it reaches maturity with one of the 

 thousands of degrees of development, between 

 which at the beginning it had a free choice. 



