OBJECTIONS TO THE THEORY OF NATURAL SELECTION 201 



other species of Oxalis with the same result; in some of them the 

 movement was distinct, but was best seen in the young leaves; in 

 others it was extremely slight. It is a more important fact that ac- 

 cording to the high authority of Hofmeister, the young shoots and 

 leaves of all plants move after being shaken; and with climbing 

 plants it is, as we know, only during the early stages of growth 

 that the foot-stalks and tendrils are sensitive. 



It is scarcely possible that the above slight movements, due to 

 a touch or shake in the young and growing organs of plants, can 

 be of any functional importance to them. But plants possess, in 

 obedience to various stimuli, powers of movement, which are of 

 manifest importance to them; for instance, toward and more rarely 

 from the light — in opposition to, and more rarely in the direction 

 of, the attraction of gravity. When the nerves and muscles of an 

 animal are excited by galvanism or by the absorption of strychnine, 

 the consequent movements may be called an incidental result, for 

 the nerves and muscles have not been rendered specially sensitive 

 to these stimuli. So with plants it appears that, from having the 

 power of movement in obedience to certain stimuli, they are ex- 

 cited in an incidental manner by a touch or by being shaken. 

 Hence there is no great difficulty in admitting that in the case of 

 leaf-climbers and tti.dril-bearers, it is this tendency which has 

 been taken advantage of and increased through natural selection. 

 It is, however, probable, from reasons which I have assigned in 

 my memoir, that this will have occurred only with plants which 

 had already acquired the power of revolving, and had thus become 

 twiners. 



I have already endeavored to explain how plants became twin- 

 ers, namely, by the increase of a tendency to slight and irregular 

 revolving movements, which were at first of no use to them; this 

 movement, as well as that due to a touch or shake, being the inci- 

 dental result of the power of moving, gained for other and bene- 

 ficial purposes. Whether, during the gradual development of 

 climbing plants, natural selection has been aided by the inherited 

 effects of use, I will not pretend to decide ; but we know that cer- 

 tain periodical movements, for instance the so-called sleep of 

 plants, are governed by habit. 



I have now considered enough, perhaps more than enough, of 

 the cases, selected with care by a skilful naturalist to prove that 

 natural selection is incompetent to account for the incipient stages 

 of useful structures; and I have shown, as I hope, that there is no 

 great difficulty on this head. A good opportunity has thus been 



