PRACTICAL POLLINATION 253 



and after taking the pollen from the stamens, 

 straighten up again. 



With the rue, the arrangement is curiously 

 complex and machinelike. Of the several 

 stamens, each in turns bestows its pollen on the 

 pistil at their common center. It has been 

 obser^^ed that the stamens advance alternately, 

 numbers one, three, and five in turn; numbers 

 two, four, and six following in succession, as if the 

 entire mechanism were actuated by clockwork. 



But these and sundry other ingenious mech- 

 anisms for self-fertilization after all only evi- 

 dence the resourcefulness of a plant in its 

 struggle for self-preservation. 



It is better that a flower should be self-poUen- 

 ized than that it should not be poUenized at all. 

 But the process is in no wise comparable, in its 

 value for the race, to the more usual process of 

 cross- fertilization. 



The self- fertilized plant develops fixity of race. 

 It lacks the needed stimulus of the blending of 

 different racial strains. It will produce few 

 varieties, thus giving little opportunity for the 

 operation of natural selection. 



In a word, such a plant is really marked for 

 ultimate extinction, unless, as in the case of the 

 wheat, man steps in to give it the refuge of 

 artificial selection. 



