THE KERNING OF THE WHEAT. 187 



not since compelled any increase of size in the wild 

 plants, constant selection lias produced a great increase 

 in the cultivated varieties. It must not, however, be 

 inferred that no changes whatever have since come over 

 the wild kinds in any respect ; as in all other cases, 

 there has been change and modification in minor matters 

 proportionate to the lapse of time which has since inter- 

 vened. But a lapse which makes relatively little differ- 

 ence to the stable wild weeds makes relatively great 

 differences in the very plastic and carefully selected cul- 

 tivated plants. 



