in accommodation to the changes which must continue in the inanimate and habitable earth, the idea struck me as the grandest which I had ever conceived, so far as regards the attributes of the Presiding Mind."

In a succeeding paragraph, Lyell very remarkably foreshadows Darwin's "natural selection" and "struggle for existence." He speaks of a species being rendered more prolific in order to perpetuate its existence; "but this would perhaps make it press too hard upon other species at other times. Now if it be an insect it may be made in one of its transformations to resemble a dead stick, or a leaf, or a lichen, or a stone, so as to be somewhat less easily found by its enemies; or if this would make it too strong, an occasional variety of the species may have this advantage conferred on it; or if this would be still too much, one sex of a certain variety. Probably there is scarcely a dash of colour on the wing or body of which the choice would be quite arbitrary, or which might not affect its duration for thousands of years." The significance of the last sentence is immense, and when we reflect that this bold but cautious thinker was in constant intercourse with Darwin, we can readily comprehend why the second edition of the Journal was so enthusiastically dedicated to Lyell. On page 481 of the "Origin of Species," Darwin acknowledges that the belief that species were immutable productions was almost unavoidable, as long as the history of the world was thought to be of short duration: which affords another proof how profoundly Lyell's views on the long duration of the past history of the globe, and its modification by the slow operation of existing causes, in

fluenced Darwin, and led him to comprehend how species might be modified.

We see Darwin, then, possessed of the idea that species are mutable, informed as to past and recent changes in the animal, plant, and physical world, seeking for causes which should suffice to produce modification of species by a continuous law. The next step in his progress was attention to domestic animals and cultivated plants. As he wrote in 1864 to Haeckel, one of his most brilliant followers: "In South America three classes of facts were brought strongly before my mind. Firstly, the manner in which closely-allied species replace species in going southward. Secondly, the close affinity of the species inhabiting the islands near South America to those proper to the continent. This struck me profoundly, especially the difference of the species in the adjoining islets in the Galapagos Archipelago. Thirdly, the relation of the living Edentata and Rodentia to the extinct species. I shall never forget my astonishment when I dug out a gigantic piece of armour like that of the living armadillo.

"Having reflected much on the foregoing facts, it seemed to me probable that allied species were descended from a common ancestor. But during several years I could not conceive how each form could have been modified so as to become admirably adapted to its place in nature. I began, therefore, to study domesticated animals and cultivated plants, and after a time perceived

I

* In this study Darwin came into communication, as early as 1839, with the Hon. and Rev. W. Herbert, afterwards Dean of Manchester, and received from him a personal account of his experiments on hybrids. It was Herbert who, as early as 1822, in the fourth

that man's power of selecting and breeding from certain individuals was the most powerful of all means in the production of new races. Having attended to the habits of animals, and their relations to the surrounding conditions, I was able to realise the severe struggle for existence to which all organisms are subjected; and my geological observations had allowed me to appreciate, to a certain extent, the duration of past geological periods. With my mind thus prepared, I fortunately happened to read Malthus's 'Essay on Population;' and the idea of natural selection through the struggle for existence at once occurred to me. Of all the subordinate points in the theory, the last which I understood was the cause of the tendency in the descendants from a common progenitor to diverge in character." I

Malthus taught the inevitable tendency of all animal life to increase beyond the means of subsistence, and expounded the checks which begin to act when population increases too rapidly. But his book had lain unfruitful to naturalists since 1798, until Darwin read it, volume of the "Horticultural Transactions," and in his work on the Amaryllidacex, 1837, declared that horticultural experiments have established, beyond the possibility of refutation, that botanical species are only "a higher and more permanent class of varieties.” He extended the same view to animals, and believed that single species of each genus were originally created in a highly plastic condition, and that these have produced, chiefly by intercrossing, but also by variation, all our existing species.

'The first portion of this important letter is quoted from the English translation of Haeckel's "History of Creation," 1876; the second portion from O. Schmidt's "Doctrine of Descent and Darwinism," having been re-written by Darwin from the German

text.

and with his special knowledge evolved from it the brilliant idea of the preservation of better-equipped races in the struggle for life, or, as Herbert Spencer put it, the survival of the fittest. At one bound the gloomy revelations of misery which the "Essay on Population" contained, were exchanged for the bright view of perpetual progress and improvement as being necessitated and brought about by the very struggle which ensued upon the natural increase of animal and plant life. Instead of struggle and pain, producing starvation and extinction merely, struggle and pain were seen as the conditions of development and improvement; the death of the lower, the life of the higher.

It is less profitable here to attempt to sketch the history of ideas of evolution in general, because that history as now revealed by research, and as detailed by many writers, was not the path along which Darwin travelled. Indeed, many of these ideas were not disinterred, and certainly were not brought to Darwin's notice till after the publication of the "Origin of Species." True he read Robert Chambers's "Vestiges of Creation," which, with its "powerful and brilliant style," although displaying in its earlier editions "little accurate knowledge and a great want of scientific caution," Darwin acknowledges to have done excellent service in calling attention to the subject, in removing prejudice, and in preparing the ground for the reception of analogous views. Mr. Herbert Spencer, in his Essay on the Development Hypothesis, first published in The Leader in March, 1852, and republished in his "Essays" (first series, 1858), argued that species have been modified owing to change of cir

cumstances, basing his argument upon the analogy of domestic animals and plants, the changes which the embryos of many species undergo, and the difficulty of distinguishing species and varieties.

But we need not here dwell on the works of these thinkers, important as they are to the general history of evolutionary thought, because Darwin's speculations had taken form long before, and he could be but slightly indebted to them. Far in advance of them he was at work collecting and testing the facts which alone could win general support for his views, and experimenting incessantly with the same object in view. Lyell and Hooker were in his confidence, and in Lyell's letters we meet with references such as the following, dated November 13, 1854: "You probably know about this (the remarkable orchid, Catasetum), which will figure in C. Darwin's book on 'Species,' with many other 'ugly facts,' as Hooker, clinging like me to the orthodox faith, calls these and other abnormal vagaries," showing at the same time how completely Darwin was the leader, while his friends, advanced as they were, hung back. Again (Lyell to Hooker, July 25, 1856): "Whether Darwin persuades you and me to renounce our faith in species (when geological epochs are considered) or not, I foresee that many will go over to the indefinite modifiability doctrine."

Further light is thrown on the progress of ideas on species by Sir Joseph Hooker's admirably written Introductory Essay to the "Flora Nova Zelandia," dated November, 1853, in which he discusses among other questions, "The Limits of Species; their Dispersion and