NATURAL SELECTION V. ADAPTATION. 



75 



Darwin himself most distinctly repudiated all power in natural selection 

 io give rise to variations of structure. His words are : " The direct action 

 of the conditions of life, whether leading to definite or indefinite results, 

 is a totally distinct consideration from the effects of natural selection ; 

 for natural selection depends on the survival under various and complex 

 circumstances of the best fitted individuals, but has no relation whatever 

 to the primary cause of any modification of structure." * 



Similarly he wrote elsewhere, speaking of " the occurrence of profitable 

 variations " under " changed conditions " : — " Unless such occur, natural 

 selection can do nothing." t 



This will be sufficient to clear the ground of any misapprehensions 

 that may exist in the mind of any reader. 



Alluding to his metaphorical use of the term "natural selection," 

 Darwin says : — "It may metaphorically be said that natural selection is 

 •daily and hourly scrutinising, throughout the world, the slightest 

 variations, rejecting those that are bad, preserving and adding up all 

 that are good, silently and insensibly working, whenever and wherever 

 opportunity offers, at the improvement of each organic being in relation 

 to its organic and inorganic conditions of life." X 



Darwin and Wallace, moreover, repeatedly use expressions about 

 natural selection as if it were a real agent ; and it is doubtless due to this 

 that so many have been misled. Thus Darwin writes about insects in the 

 following strain : — " Natural Selection may modify and adopt the larva 

 ■of an insect to a score of contingencies wholly different from those 

 which concern the mature insect. ... In all cases natural selection will 

 ensure that they shall not be injurious." 



" Natural selection will modify the structure of the young in relation 

 to the parent " &c. § 



Similarly Wallace writes, in speaking of the evolution of man, how he 

 would be "subject to the irresistible action of natural selection" . . . 

 which " would most powerfully act " &c. 



These few quotations will be sufficient for the reader to bear in mind 

 that natural selection does nothing. If a being survives, it is because it 

 has sufficient means of support and can live under the circumstances of 

 its existence. If it dies, it does so because it has reached its normal end, 

 or it has not enough food, or is killed by other beings or by some in- 

 organic forces. The difference is designated by the words " natural selec- 

 tion ' ' ; that is all. 



Now let us see what Darwin meant by "indefinite variations," for the 

 entire theory which has been called " Darwinism " depends upon it. || He 

 says : — " The direct action of changed conditions leads to definite or 

 indefinite results. In the latter case the organisation seems to become 

 plastic, and we have much fluctuating variability." He has here in his 

 mind what occurs in the garden, not in nature at all. " In the former 

 ■case," he adds, " the nature of the organism is such that it yields 

 readily when subjected to certain conditions, and all or nearly all the 



* Animals and Plants under Domestication, vol. ii. p. 272. 

 f Origin Ac, p. 64. % Origin &-e., p. 65. § Origin &c, p. 67. 



|| I would again remind the reader not to confound Darwin's theory of " the 

 rigin of species by means of natural selection " with evolution itself. 



