On the occasion of the celebration at Cambridge in 1909 of the centenary of Darwin’s birth, I was invited by the Vice-Chancellor, on behalf of the University, to deliver in the Senate-house an address, others being given by representatives of the United States (Prof. Osborne), of Germany (Prof. Hertwig), and of Russia (Prof. Metchnikoff). The following is the text of that address:— “I feel it a great honour to be called upon to speak here to-day, and to stand, on behalf of the naturalists of the British Empire, by the side of the distinguished men whose orations you have just heard. “I think that the one thing about Charles Darwin which the large majority of British naturalists would wish to be to-day proclaimed, in the first place—with no doubtful or qualifying phrase—is that, in their judgment, after these fifty years of examination and testing, his ‘theory of the origin of species by means of natural selection or the preservation of favoured races in the struggle for life’ remains whole and sound and convincing, in spite of every attempt to upset it. “I am not stating more than the simple truth when I say that, in the judgment of those who are best acquainted with living things in their actual living surroundings, ‘natural selection’ retains the position which Mr. Darwin claimed for it of being the main means of the modification of organic forms. “Our admiration for the vast series of beautiful observations and interesting inquiries carried out by Darwin during his long life must not lead us to forget that they were devised by him in order to test the truth of his theory and to meet objections to it, and that they were triumphantly successful. They, together with the work of Alfred Russel Wallace and many of their followers, have more and more firmly established Darwin’s theory. On the other hand, no attempt to amend that theory in any essential particular has been successful. “The nature of organic variation and of the character of the variations upon which natural selection can and does act was not, as we are sometimes asked to believe, neglected or misapprehended by Darwin. The notion that these variations are large and sudden was considered by him, and for reasons set forth by him at considerable length rejected. That notion has in recent years been resuscitated, but its truth has not been rendered probable by evidence either of such an accurate character or of such pertinence as would justify the rejection of Darwin’s fundamental conception of the importance of minute and ubiquitous variations.