WCP5623

[1] [p. 40]

TO MRS. FISHER (neé BUCKLEY)¹

Frith Hill, Godalming.² February 16, 1888.

My dear Mrs. Fisher, — I know nothing of the physiology of ferns and mosses, but as a matter of fact I think they will be found to increase and diminish together all over the world. Both like moist, equable climates and shade, and are therefore both so abundant in oceanic islands, and in the high regions of the tropics.

I am inclined to think that the reason ferns have persisted so long in competition with flowering plants is the fact that they thrive best in shade, flowers best in the light. In our woods and ravines the flowers are mostly spring flowers, which die away just as the foliage of the trees is coming out and the shade deepens; while ferns are often dormant at that time, but grow as the shade increases.

Why tree ferns should not grow in cold countries I know not, except that it may be the winds are too violent and would tear all the fronds off before the spores were ripe. Everywhere they grow in ravines, or in forests where they are sheltered, even in the tropics. And they are not generally abundant, but grow in particular zones only. In all the Amazon valley I don't remember ever having seen a tree-fern....

I too am struggling with my "Popular Sketch of Darwinism,"³ and am just now doing a chapter on the great "hybridity" question. I really think I shall be able to arrange the whole subject more intelligibly than Darwin did, and simplify it immensely by leaving out the endless discussion of collateral details and difficulties which in the "Origin of Species"⁴ confuse the main issue....

[2] The most remarkable steps yet made in advance are, I think, the theory of Weismann⁵ of the continuity of the germ plasm, and its corollary that acquired modifications are never inherited! and Patrick Geddes's⁶ explanation of the laws of growth in plants on the theory of the antagonism of vegetative and reproductive growth.... —

Yours very sincerely, | ALFRED R. WALLACE.