272 Colour and the Struggle for Life 



dioecious floAvers ; but it is well to remember that their colours may 

 be as unimportant to them as those of a gall, or, indeed, as the colour 

 of an amethyst or ruby is to these gems 1 ." 



Incidental colours remain as available assets of the organism ready 

 to be turned to account by natural selection. It is a probable specu- 

 lation that all pigmentary colours were originally incidental ; but now 

 and for immense periods of time the visible tints of animals have been 

 modified and arranged so as to assist in the struggle with other 

 organisms or in courtship. The dominant colouring of plants, on the 

 other hand, is an essential element in the paramount physiological 

 activity of chlorophyll. In exceptional instances, however, the shapes 

 and visible colours of plants may be modified in order to promote 

 concealment 2 . 



Teleology and Adaptation. 



In the department of Biology which forms the subject of this essay, 

 the adaptation of means to an end is probably more evident than in 

 any other ; and it is therefore of interest to compare, in a brief 

 introductory section, the older with the newer teleological views. 



The distinctive feature of Natural Selection as contrasted with 

 other attempts to explain the process of Evolution is the part played 

 by the struggle for existence. All naturalists in all ages must have 

 known something of the operations of " Nature red in tooth and 

 claw"; but it was left for this great theory to suggest that vast 

 extermination is a necessary condition of progress, and even of main- 

 taining the ground already gained. 



Realising that fitness is the outcome of this fierce struggle, thus 

 turned to account for the first time, we are sometimes led to associate 

 the recognition of adaptation itself too exclusively with Natural 

 Selection. Adaptation had been studied with the warmest enthusiasm 

 nearly forty years before this great theory was given to the scientific 

 world, and it is difficult now to realise the impetus which the works 

 of Paley gave to the study of Natural History. That they did inspire 

 the naturalists of the early part of the last century is clearly shown in 

 the following passages. 



In the year 1824 the Ashmolean Museum at Oxford was intrusted 

 to the care of J. S. Duncan of New College. He was succeeded in 

 this office by his brother, P. B. Duncan, of the same College, author 

 of a History of the Museum, which shows very clearly the influence of 

 Paley upon the study of nature, and the dominant position given to 

 his teachings : "Happily at this time [1824] a taste for the study of 



1 More Letters of Charles Darwin, Vol. i. pp. 354, 355. See also the admirable 

 account of incidental colours in Descent of Man ('2nd edit.), 1874, pp. 261, 202. 



2 See pp. 273, 276. 



