No. 565] CHANGES PRODUCED BY SELECTION 21 



24 leaves, and as the strain indicated that it was hetero- 

 zygous for a number of factors by showing a coefficient of 

 variability of 8.29 ± .42 per cent-, it is possible that the 

 selected parent plant may have belonged gametically to a 

 higher class than was indicated somatically ; nevertheless, 

 it can not be denied that three generations of selected 

 minus extremes have produced no results. This conclu- 

 sion is not valid for the plus strain. Starting with 26.3 ± 

 .10 as the mean number of leaves (F 5 ), the succeeding gen- 

 erations had means of 27.1 ± .07 leaves, 28.3 ± .11 leaves 

 and 30.0 ± .11 leaves. The differences are 0.8, 12 and 1.7 

 leaves, respectively. Progressive change has certainly f ol- 



