THEORIES OF LAMARCK AND DARWIN 395 



tomed to display their tail-feathers; the one with the most 

 attractive display excites the pairing instinct in the highest 

 degree, and becomes the selected suitor. In this way, 

 through the operation of a form of selection which Darwin 

 designates sexual selection, possibly such curious adaptations 

 as the peacock's tail may be accounted for. 



It should be pointed out that this part of the theory is 

 almost wholly discredited by biologists. Experimental evi- 

 dence is against it. Nevertheless in a descriptive account 

 of Darwin's theory it may be allowed to stand without 

 critical comment. 



Inadequacy of Natural Selection. In nature, under the 

 struggle for existence, the fittest will be preserved; and natural 

 selection will operate toward the elaboration or the suppres- 

 sion of certain organs or certain characteristics when the elab- 

 oration or the suppression is of advantage to the animal form. 

 Much has been said of late as to the inadequacy of natural 

 selection. Herbert Spencer and Huxley, both accepting 

 natural selection as one of the factors, doubted its complete 

 adequacy. 



One point is often overlooked, and should be brought out 

 with clearness; viz., that Darwin himself was the first to 

 point out clearly the inadequacy of natural selection as a 

 universal law for the production of the great variety of 

 animals and plants. In the second edition of the Origin of 

 Species he says: "But, as my conclusions have lately been 

 much misrepresented, and it has been stated that I attribute 

 the modification of species exclusively to natural selection, 

 I may be permitted to remark that in the first edition of this 

 work and subsequently I placed in a most conspicuous 

 position, namely, at the close of the introduction the follow- 

 ing words: 'I am convinced that natural selection has been 

 the main, but not the exclusive means of modification.' This 

 has been of no avail. Great is the power of steady mis- 



