90 



JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



ON THE TRUE MEANING OF " NATURAL SELECTION " 

 AND THE " SURVIVAL OF THE FITTEST " IN NATURE. 



By the Rev. Professor G. Henslow, M.A., V.M.H., &c. 



[Lecture given on September 12, 1905.] 



In a lecture delivered in 1903 on " Natural Selection v. Adaptation, or 

 Darwinism and Evolution," * I explained the use of the term " natural 

 selection" as employed by Darwin in his theory on "The Origin of 

 Species by Means of Natural Selection" — the title of his well-known 

 book, published in 1859. I also pointed out that he tells us that he took 

 the idea of natural selection from Malthus' " Essay on Population," but 

 by inserting "structure" and "form," upon which species are solely 

 based, he went beyond the application of natural selection by Malthus, 

 since the latter was solely concerned with human beings. 



Plants and animals do not die in consequence of slight variations of 

 form. Darwin's theory, therefore, falls to the ground. 



Natural selection, however, stands for a very real fact of nature ; 

 for, since the offspring of animals and plants are so numerous, it would 

 be impossible for all to live, so that the vast majority perish in the young 

 state as well as in the perpetual contests between them when adult. It 

 is in this incessant struggle for life, whether in competing with other 

 plants for the same ground, or in overcoming the difficulties of an in- 

 hospitable soil and climate, often without any neighbours at all, that 

 natural selection is most in evidence. It must be remembered that it is 

 only a name for the result of the struggle. The reason why some live 

 and others die can be explained by the conditions of life alone. 



The latest description of natural selection has been recently given by 

 Professor G. H. Darwin, F.R.S., in his Presidential Address before the 

 members of the British Association at Cape Town. He is reported to 

 have said : " The fundamental idea in the theory of natural selection is 

 the persistence of those types of life which are adapted to their sur- 

 rounding conditions, and the elimination by extermination of ill-adapted 

 types." 



But, apart from abnormal monstrosities, nature has never been known 

 to make " ill-adapted types." 



When, however, two types are struggling together, say grass and 

 colt's-foot, each may be equally well adapted to thrive if the other were 

 absent. If a better adapted plant invade the territory of another, such 

 as the colt's- fo3t among grass by a roadside, it may bring about the 

 extermination of the grass by shutting off light and by starvation. 

 Similarly, if seeds fall among grass or on sandy barren soil, they may 

 fail to grow, even if they germinate at all. 



Such I take to be the true and only kinds of the struggle for existence 

 to which natural selection can be legitimately applied. There is no 

 * Journal of the Eoyal Horticultural Society, vol. xxviii., part i. 



