Artificial and Natural Selection 813 



nary sowings. Originally he had made his cul- 

 tures for the improvement of his own fields only. 

 Gradually however, he began to sell his product 

 as seed to others, though he found the difference 

 still very slight. After ten years more, about 

 1886, he was able to sell all his rye as seed, 

 thereby making of course large profits. It is 

 now acknowledged as one of the best sorts, 

 though in his last letter Mr. Eimpau announced 

 to me that the profits began to decline as other 

 selected varieties of rye became known. The 

 limit of productiveness was reached, and to sur- 

 mount this, selection had to be begun again 

 from some new and better starting point. 



This new starting point invokes quite another 

 principle of selection, a principle which threat- 

 ens to make the contrast between artificial and 

 natural selection still greater. In fact it is noth- 

 ing new, being in use formerly in the selection 

 of domestic animals, and having been applied 

 by Vilmorin to his sugar-beets more than half a 

 century ago. Why it should ever have been 

 overlooked and neglected in the selection of 

 sugar-beets now is not clear. 



The principle in itself is very simple. It 

 agrees that the visible characters of an animal 

 or a plant are only an imperfect measure for its 

 hereditary qualities, instead of being the real 

 criterion to be relied upon, as is the current be- 



