Page:Popular Science Monthly Volume 26.djvu/725

Rh indications of the original home of cultivated plants are incomplete or incorrect. His statements have since been repeated, and, in spite of what modern writers have proved touching several species, they are still repeated in periodicals and popular works. It is time that mistakes, which date in some cases from the Greeks and Romans, should be corrected. The actual condition of science allows of such correction, provided we rely upon evidence of varied character, of which some portion is quite recent, and even unpublished; and this evidence should be sifted as we sift evidence in historical research. It is one of the rare cases in which a science founded on observation should make use of testimonial proof. It will be seen that this method leads to satisfactory results, since I have been able to determine 'the origin of almost all the species, sometimes with. absolute certainty, and sometimes with a high degree of probability.

The investigations of De Candolle assume a new and enlarged interest from the results of modern biological progress in regard to the transformations of species, and the vast periods of time during which organic development and mutations have been going forward. The great problem was fundamentally changed with the abandonment of the old view regarding the immutability of species. It was under the careful study of plants that that view first broke down, and from that time a radically new method has prevailed in the study of the vegetable kingdom. From this point of view the historical question of the origin of cultivated plants not only became a modern question, belonging, indeed, to the present age, and incapable of earlier solution, but it connects itself with vast periods of change, and is linked on to the largest considerations of the economy of life upon the earth. We quote some further instructive observations of our author in regard to important particulars of his research:

I have endeavored to establish the number of centuries or thousands of years during which each species has been in cultivation, and how its culture spread in different directions at successive epochs. A few plants cultivated for more than two thousand years, and even some others, are not now known in a spontaneous, that is, wild condition, or at any rate this condition is not proved. Questions of this nature are settled. They, like the distinction of species, require much research in books and herbaria. 1 have even been obliged to appeal to the courtesy of travelers or botanists in all parts of the world to obtain recent information. I shall mention these in each case, with the expression of my grateful thanks.

In spite of these records and of all my researches there still remain several species which are unknown wild. In the cases where these come from regions not completely explored by botanists, or where they belong to genera as yet insufficiently studied, there is hope that the wild plant may be one day discovered. But this hope is fallacious in the case of well-known species and countries. We are here led to form one of two hypotheses: either these plants have since history began so changed in form in their wild as well as in their cultivated condition that they are no longer recognized as belonging to the same species, or they are extinct species. The lentil, the chick-pea, probably no longer exist in nature; and other species, as wheat, maize, the broad bean, carthamine, very rarely found wild, appear to be in course of extinction. The number of cultivated plants with which I am here concerned being 249, the three, four, or five species, extinct or nearly extinct, is a large proportion, representing a thousand species out of the whole number of phanerogams. This destruction of forms must have taken place during the short period of a few hundred centuries, on continents where they might have spread, and under circumstances which are commonly considered unvarying. This shows how the history of cultivated plants is allied to the most important problems of the general history of organized beings.

From these considerations it will be seen that the present volume is of capital interest to all concerned with botanical science. It is an authoritative digest of facts to be nowhere else found, and has been executed with the strictest fidelity to the original sources of information. The fullness and minuteness of the references to works consulted greatly enhance the scientific value of the volume, and will undoubtedly be much appreciated by botanical students.

But, as we remarked at the outset, the book is entirely popular, and thoroughly intelligible to common readers. Its plan is simple. Part I consists of two chapters of general preliminary remarks as to I, "In what Manner and at what Epochs Cultivation began in Different Countries"; and II, "Methods for discovering or proving the Origin of Species." In Part II, the main portion of the work, the divisions are simple and practicable, as follows: I, "Plants cultivated for their Subterranean Parts, such as Roots, Tubercles, or Bulbs"; II, "Plants cultivated for their Stems or Leaves"; III, "Plants cultivated for their Flowers, or the Organs which envelop them"; IV, "Plants cultivated for their Fruits"; V, "Plants cultivated for their Seeds." At the close there in a valuable table summing up the general results, which is followed by a careful index. All the