ACQUIREMENT VERSUS SELECTION 455 



perfect adaptations to its strange environment. We are 

 warranted in believing that tliese plants could not live there 

 unless they had some such adaptations, ])ut just where ex- 

 treme adaptations are most necessary there is least compe- 

 tition to account for them. But may not the environment 

 operate selectively nevertheless? Perhaps, but even so it is 

 not through the struggle of numerous competing individuals: 

 any one of them that is favorably situated and is just able to 

 stand the worst of the drought has as good a chance to in- 

 crease and multiply as the toughest of all. It may also be 

 pointed out that the most marked features of desert plants — 

 such for example as extensive root system, succulent or 

 greatly reduced foliage, hairy or thickened skin for checking 

 loss of water, and an armament of thorns for defense against 

 animals — are the ones most easily accounted for as originat- 

 ing from direct effect of the environment or individual re- 

 sponse; while as regards the defensive armament, Avhich is 

 often cited as a most perfect adaptation, it must be said, 

 that grave doubts are raised as to its being of much use in 

 the very cases where it is most forbidding, since few if any 

 large browsing animals are found in those localities where 

 the most highly developed armaments occur. In such cases 

 any selective influence is hard to imagine. 



Naturalists have found many cases in which a selective 

 influence, supposing it to exist, would have no opportunity 

 to act upon small fluctuating variations in the Darwinian 

 way. The climbing habit of clematis will serve to show 

 what is meant. The coiling of the leaf-stalks by unequal 

 growth stimulated by contact with a support, is an undoubt- 

 edly useful power; but this power, it would seem, can be of 

 service only after it is developed; a very slight curving of the 

 stalk could not anchor a leaf. Therefore we cannot reason- 

 ably suppose that the power to coil was developed from slight 

 curving rendered more pronounced in successive generations 

 by natural selection. Here it is the first step that counts, 

 and it is just this step that the theory of natural selection 

 is often unable to take. 



Artificial selection, not being restricted in its operation 

 to variations of use to the plant, does not offer so close an 



