ness with which Dr. Darwin had conceived the principle of development, or of the astonishing quickness of perception with which he laid hold of facts in support of his view. It is simply marvellous that a man so immersed as he was in the cares of a most extensive and laborious medical practice could have mustered together from his own reading and observation such an array of proofs. No doubt something of his scientific and literary productiveness is due to the fact that Dr. Darwin, while riding in the practice of of his profession, "read and wrote much in his carriage, which was fitted up for the purpose."

As is natural enough, we find, on coming from Dr. Darwin to Lamarck, a great advance in exact comprehension and statement of the doctrine of descent. In his "Zoological Philosophy," published from 1815 to 1822, occurs the following passage: :

"The systematic divisions of classes, orders, families genera, and species, as well as their designations, are the arbitrary and artificial productions of man. The kinds or species of organisms are of unequal age, developed one after the other, and show only a relative and temporary persistence species arise out of varieties. The differences in the conditions of life have a modifying influence on the organization, the general form, and the parts of animals, and so has the use or disuse of organs. In the first beginning, only the very simplest and lowest animals

and plants came into existence; those of a more complex organization, only at a later period. The course of the earth's development and that of its organic inhabitants was continuous, not interrupted by violent revolutions." 1

Of these opinions Haeckel says,

"These are indeed astonishingly bold, grand, and farreaching views, and were expressed by Lamarck sixty years ago; in fact, at a time when their establishment by a mass of facts was not nearly as possible as it is in our day."

On account of the determined hostility of Cuvier and the unfriendliness of Napoleon to Lamarck, his labors remained for almost half a century comparatively unregarded. But during all this time naturalists were again and again recurring to the question of the origin of species'; so that, from the year 1790 till 1858, there was hardly a period of five years in which the doctrine of descent was not stated in some form by somebody. In all, more than thirty naturalists and philosophers had by the year 1858 enunciated principles which tended more or less strongly to confirm the truth of the development theory.2 But it was not till July 1, 1858,

1 Quoted by Haeckel, Natural History of Creation, i. pp. 112, 113.

2 Historical sketch preceding Darwin's Origin of Species, also Haeckel's Natural History of Creation, chaps. iv., v.

that the theory was put before the world in a form so authoritative as to compel a hearing, if not an unqualified acceptance, for it, from every man of science. For on this date two papers were read before the Linnæan Society of London, which were to work a revolution in the current modes of thought, not only among zoologists and botanists, but also among students of many widely separated branches of human knowledge. One of these papers had been forwarded from the East Indies by Alfred Russell Wallace, and contained the result of his observations "On the Tendency of Varieties to depart indefinitely from the Original Type." The other paper, on The Origin of Species," by Charles Darwin, was the result of over twenty years of study. Speaking of some of his observations while engaged as a naturalist on a trip round the world, and of the light which these observations seemed likely to throw on the origin of species, Mr. Darwin himself says,

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“On my return home it occurred to me, in 1837, that something might perhaps be made out on this question by patiently accumulating and reflecting on all sorts of facts which could possibly have any bearing on it. After five years' work, I allowed myself to speculate on the subject, and drew up some short notes: these I enlarged in 1844 into a sketch of the conclusions which then seemed

to me probable. From that period to the present day [1859] I have steadily pursued the same object." 1

And the last sentence above quoted was as true at the time of the great naturalist's death, in 1882, as at the date when it was written.

How great Darwin's work was, can nowhere better be learned than in Mr. Wallace's article, "The Debt of Science to Darwin." 2 No one can read this unselfish tribute to Darwin's greatness without forming a high opinion of Wallace as well; for it must be remembered that the latter was an independent discoverer of the origin of species by means of natural selection.

Briefly stated, the reason why Darwin, by general consent, is ranked as one of the foremost scientific men of all time is, that he united, to a degree never surpassed, the genius for making observations and that for reasoning from the results of observation. By possessing both of these rare endowments in the highest degree, Darwin was enabled to do what all other naturalists had failed to accomplish; that is, not only to state that species are descended from other species, but also to prove the truth of the statement, and to show how the process of specific

1 Introduction to the Origin of Species. See, also, The Life and Letters of Charles Darwin, American edition, vol. I., pp. 67-71, and ch. x. to xiii.

2 Century Magazine, January, 1883.

change was brought about, and new species perpetuated.

Dr. Darwin and Lamarck, indeed, brought forward, in support of the theory of descent, such facts as were known in the latter part of the last and the beginning of the present century; but the best explanation of the derivation of new species that they could give was the supposition that the habits and the wishes of any animal finally brought about such adaptations in its body as were demanded by the conditions of its life. The giraffe, for example, owed its long neck to the fact that its ancestors had for many generations wished and endeavored to reach branches of trees high above the ground, and so gradually the required increase in length of neck was developed.

Of any such powerful agency as natural selection operating to preserve advantageous variations, neither Dr. Darwin nor Lamarck had any conception at all equal to that of Charles Darwin.1

1 Dr. Darwin, however, well understood the principle of sexual selection: after a number of other examples of the same general tenor, he says,

"The birds which do not carry food to their young, and do not therefore marry, are armed with spurs, for the purpose of fighting for the exclusive possession of the females, as cocks and quails.