Publisher's Synopsis
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1896 edition. Excerpt: ... CHAPTER XIV. THE PAST HISTORY OF PLANTS. I Promised some time since to return in due season to the question why plants, as a rule, exhibit distinct kinds or species, instead of merging gradually one into another by imperceptible degrees. This problem is generally known as the problem of the origin of species. You might perhaps expect (since plants have grown and developed, as we have seen, one out of the other) that they would consist at present of an unbroken series, each melting into each, from the highest to the lowest. This, however, is not really the case; they form on the contrary groups of distinct kinds: and the reason is, that natural selection acts on the whole in the opposite direction. It tends to make plants group themselves into definite bodies or species, all alike within the body, and well marked off from all others outside it. Here is the way this arrangement comes about. As situations and circumstances vary, a form is at last arrived at in each situation which approximately fits the particular circumstances. This form may perhaps vary again in other situations, and give rise to individuals better adapted to the second set of circumstances. But just in proportion as such individuals surpass in adaptation one another will they live down the less adapted. Hence, the intermediate forms will tend to perish, and the world to be filled in the end with groups of plants, each distinct from others, and each relatively fixed and similar within its own limits. At all times, and in all places, this process of variation and adaptation is continually going on; new kinds are being formed, and intermediates are dying out between them. For the intermediates are necessarily less adapted than the older form to the old conditions, and than...