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Variation." While still adhering on the whole to the origin of species from single parents, or from one pair, and the permanence of specific characters, he insists that species vary more, and are more widely distributed, than is generally admitted, and that their distribution has been brought about by natural causes. In this essay he makes the following statements: "Mr. Darwin not only directed my earliest studies in the subjects of the distribution and variation of species, but has discussed with me all the arguments, and drawn my attention to many of the facts which I have endeavoured to illustrate in this essay. I know of no other way in which I can acknowledge the extent of my obligation to him, than by adding that I should never have taken up the subject in its present form but for the advantages I have derived from his friendship and encouragement."

Appropriately enough, it was through Lyell and Hooker that the new theory was introduced to the public, and it was owing to them that Darwin did not obliterate his own claims to priority, and give them over to Alfred Russel Wallace, who had indepen+ dently come to similar conclusions. The letter, dated June 30, 1858, in which the announcement was conveyed to the Linnean Society, deserves quotation, as being the authoritative and accurate record of the circumstances which launched the "Origin of Species " upon the world:

"The accompanying papers, which we have the honour of communicating to the Linnean Society, and which all relate to the same subject, viz., "The Laws

which affect the Production of Varieties, Races, and Species,' contain the results of the investigations of two indefatigable naturalists, Mr. Charles Darwin and Mr. Alfred Wallace.

"These gentlemen having, independently and unknown to one another, conceived the same very ingenious theory to account for the appearance and perpetuation of varieties and of specific forms on our planet, may both fairly claim the merit of being original thinkers in this important line of inquiry; but neither of them having published his views, though Mr. Darwin has been repeatedly urged by us to do so, and both authors having now unreservedly placed their papers in our hands, we think it would best promote the interests of science that a selection from them should be laid before the Linnean Society.

"Taken in the order of their dates, they consist

of

"1. Extracts from a MS. work on species, by Mr. Darwin, which was sketched in 1839, and copied in 1844, when the copy was read by Dr. Hooker, and its contents afterwards communicated to Sir Charles Lyell. The first part is devoted to 'The Variation of Organic Beings under Domestication and in their Natural State'; and the second chapter of that part, from which we propose to read to the Society the extracts referred to, is headed, 'On the Variation of Organic Beings; in a State of Nature; on the Natural Means of Selection; on the Comparison of Domestic Races and true Species.'

"2. An abstract of a private letter addressed to Professor Asa Gray, of Boston, U.S., in October, 1857, by Mr.

Darwin, in which he repeats his views, and which shows that these remained unaltered from 1839 to 1857.

"3. An essay by Mr. Wallace, entitled 'On the Tendency of Varieties to depart indefinitely from the Original Type.' This was written at Ternate in February, 1858, for the perusal of his friend and correspondent, Mr. Darwin, and sent to him with the expressed wish that it should be forwarded to Sir Charles Lyell, if Mr. Darwin thought it sufficiently novel and interesting. So highly did Mr. Darwin appreciate the value of the views therein set forth, that he proposed, in a letter to Sir Charles Lyell, to obtain Mr. Wallace's consent to allow the essay to be published as soon as possible. Of this step we highly approved, provided Mr. Darwin did not withhold from the public, as he was strongly inclined to do (in favour of Mr. Wallace) the memoir which he had himself written on the same subject, and which, as before stated, one of us had perused in 1844, and the contents of which we had both of us been privy to for many years. On representing this to Mr. Darwin, he gave us permission to make what use we thought proper of his memoir, &c.; and in adopting our present course, of presenting it to the Linnean Society, we have explained to him that we are not solely considering the relative claims to priority of himself and his friend, but the interests of science generally; for we feel it to be desirable that views founded on a wide deduction from facts, and matured by years of reflection, should constitute at once a goal from which others may start, and that, while the scientific world is waiting for the appearance of Mr. Darwin's complete work, some of the

leading results of his labours, as well as those of his able correspondent, should together be laid before the public."

In these papers, read on July 1, 1858, Darwin's share amounts to little more than six pages, yet within this space he describes the geometrical rate of increase of animals, the checks that occur, the effects of changed conditions, the natural selection of the better equipped forms resulting from the struggle for existence, and the influence of sexual selection. Wallace insists on essentially the same view, which he calls that of progression and continued divergence. "This progression, by minute steps, in various directions, but always checked and balanced by the necessary conditions, subject to which alone existence can be preserved, may, it is believed, be followed out so as to agree with all the phenomena presented by organised beings, their extinction and succession in past ages, and all the extraordinary modifications of form, instinct, and habits which they exhibit." Those who read Wallace's original essay can best appreciate the extraordinary simplicity and nobility of character which inclined the elder naturalist, who had so long held the same views, to step aside in favour of the younger man, who from different researches was led to such similar conclusions. It may here be added that Hooker, in the Introductory Essay to the "Flora Tasmania," dated November 4, 1859, before the publication of the "Origin of Species," but after seeing much of it in manuscript, accepted and advocated the view that species are derivative and mutable, and developed it as regards the geographical distribution of plants.

CHAPTER V.

D

ARWIN'S great work "On the Origin of Species by means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life," was published in November, 1859. It begins with the simplest narrative of the events leading to its publication, and an apology for the imperfection of "this abstract." The author is well aware, he says, that on most points he deals with, facts can be adduced which often apparently lead to conclusions directly opposite to his own. He states clearly the important truth that a mere belief in the origin of species by descent from other species is unsatisfactory until it can be shown how species can have been modified so as to acquire their present remarkable perfection of structure and coadaptation. Consequently cases of observed modification of species are of the highest value, and precedence is given to the variation of animals and plants in a state of domestication.

The individuals belonging to the same variety of any of our long-cultivated animals or plants differ much more from each other than the individuals of any one species or variety in a state of nature. Darwin explains this by

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