WCP2927

[1]^{1, 2}

38 Gosford Place,

Edinburgh.

March 6th 1909

Dear Sir, —

I have just been reading, in the current number of the Fortnightly Review, the interesting article in which you restate the Darwinian Theory of the Origin of Species and maintain the adequacy of the same. About your main contention I should like in a humble way simply to say this: if all other people thought about it as I do there would have been less need for you to write in defence of it. I find that the set of ideas referenced by Darwin actually works in my outlook upon organic nature, and I do not find that there is any other set of ideas in the field, to say nothing of holding it! My purpose, however, has to do with something more simple. I should like if you will permit me, to ask a question on a matter which has for some time interested me, which question rises, fairly I think, [2] out of one of your paragraphs.

But before doing this I should like to give expression to a thought which has been much in my mind for the past year or so. What a unique history in the sphere of thought has been that through which you yourself and Sir Joseph Hooker², for this name also seems in this connection, how actually paired. To have lived in pre-Darwinian days and to have been acquainted with the notion which then provided in Natural History, to have contributed to the imagination of Darwinism, and to have lived through half a century of the evolution of the set of ideas for which this name stands, till that set of ideas has influenced the whole [1 word illeg.] of thought — that, it seems to me, is an experience which has hitherto had no equal among the sum of men. To one desirous of arriving at a comprehension of the meaning of things such a history is is suggestion of great possibilities. But the meaning of [3]⁴ things" —? What multiple of long human existence will be capable of giving us that?

I return now to my question. At the end of the section in your article which deals with "Protective Colour and Mimicry," you have the following § : —

"The facts already given with regard to the universality of variation, enormous powers of multiplication, and inerrant pending out of the profit afford a complete explanation of the phen[omen]^a of colours, in all their variety and beauty, which no other adequate explanation has ever been set forth, or even attempted."

Now the question which for some time has often been in my mind, but which I have nowhere even seen stated, is this: How is it that while the prevailing colour of plants, pre-eminently of some of the foliage, is green, represented by the centre of the light spectrum, the colour of the flowers on different green plants should practically vary through all the shades of the spectrum?

[4] The raison d'ȇtre of flower-colouring in general is, I take it, that the flower may become visible to insects, hence the need of relief. But if red is a sufficient relief in one case, why green, blue, and all the other colours?

In the case of the flower which we have all been seeing for some time — the snow-drop — it seems to me we have an example of colour protection; but such an explanation can only I think be of limited application in the case of flower-colouring in general. Shall we say that flower-colouring is a matter of indifference so long as a contrast with green is maintained, that consequently anot green will do?

But there is probably something too, about this subject which we should born[?] if we know more about about are the influences involved in the different original habitat of different plants.

Begging that you will pardon the liberty I have thus taken,

I am | Yours respectfully, | David Anderson³[signature].