TO JAMES D. DANA.
June 22, 1872.
My dear Dana,—I fancy you have got hold of a good topic for your handling, and have a promising inquiry before you, in coördinating cephalization and natural selection as operative on the nervous system of animals. I expect you to get something interesting out of it.
But every now and then something you write makes me doubt if you quite get hold just right of Darwinian natural selection. What you still say about struggle not applicable to plants makes me think so.
Suppose the term be a personification, as, no doubt, strictly it is. One so fond as you are of personification and good general expressions ought not to object to what seems to me a happy term.
Speaking from general memory, I should say that the term, as used to express what we mean, was introduced by the elder De Candolle and applied in what I thought a happy way to the vegetable kingdom. I cannot drop it because you say there is no struggle where there is no will; perhaps you mean without consciousness, and then the field of struggle will be much limited. But call the action what you please,—competition (that is open to the same objection), collision, or what not,—it is just what I should think Darwin was driving at. Read “Origin” (4th ed.), pp. 72, 73, and so on, through the chapter, especially pp. 81-86.
This is enough to show you that when you speak of “Darwinian struggle” as occurring only “when the faculties of an animal are called into requisition,” you take too limited a view of what Darwin means.
For myself I should say that the faculties of the lowest animals and the faculties of plants were equally called into requisition in the case, in a manner so parallel that there is no drawing any but a purely arbitrary distinction between the one and the other.
I conceive one as effective as the other as regards the leading on and fixing variation.
When I say now again that the expression “fitted by its regional development to the region” conveys no clear meaning to me, I am only telling you, as I did before, my way of looking at things, not finding fault with yours.