294 Mr Philip Sewell on the [sess. or. 



April and July the average order of the first appearance of 

 the various colours was from blue, yellow, and white to red 

 — the order of the spectrum colours. As at the time atten- 

 tion was called to the fact that light has little or no direct 

 effect upon colour, it was thought that there was only a 

 somewhat remarkable coincidence in these facts ; but it may 

 be possible that such data, being corroborated, on compari- 

 son with other floras, may indicate to us some indirect effect, 

 following perhaps from the increased or diminished assimila- 

 tion at one or another time of the year. 



A couple of years after the date of publication of Dr 

 Buchan's paper, there appeared, also in Nature, an article on 

 " The Origin and Distribution of Organic Colour in Nature," 

 in which, after opening with the statement that " colour 

 tliroughout the realms of organic nature is a factor hitherto 

 held to be the most capricious in its distribution, and the 

 least amenable to any fixed law," the writer proceeds to 

 show that it occurs in harmony with the " law of polaris- 

 ation." He points out the prevalence of complementary 

 colours, as in the red eye-speck with the green of Volvox, or 

 in riucroncma, which is coloured orange, whilst above is the 

 cffirulean blue characteristic of the ocean in the abyssal 

 depths wliicli this organism inhabits. It is doubtful whether 

 an explanation in such terms is any more satisfactory to us, 

 than was the old truly metaphysical one which would have 

 us see in colour and form harmony with " the law of beauty 

 and design," framed to delight mankind. 



Thanks to Charles Darwin (who, in this particular re- 

 vivified the work of Sprengcl), and thanks to Hermann 

 Midler, we now know that flower-colour has its largest use 

 in gratifying the bee, and that it cannot bo spoken of as 

 " wasting its sweetness " when there are around it countless 

 insects to benefit ))y its attractiveness. 



Thus a more real use for colour became evident, and 

 natural selection was called in to explain its presence. 



Now, allowing what we wish for natural selection, we have 

 yet to ask (jurselves. What is the origin of the variations in 

 colour ? how have earlier or later variations arisen which 

 might be selected ? 



Most of those who have definitely dealt with the question 

 of colour, — treating it professedly in a ])npular maimer, as do 



