The stimulating air of Dublin had a very visible effect on the British Association. The members were in great force, and among Associates were fewer of those very unattached camp-followers who enjoy not Science but the reputation which is bought cheaply at a guinea. The name of Darwin as well as the air of Dublin no doubt added impetus to the meeting. People wanted to hear about Darwin, and one of the mistakes of the week was that they were allowed to hear so little. No speech was more popular than the few words, very beautifully said and delivered, in which Sir Archibald Geikie explained how in his later years Charles Darwin found an encyclopaedia in his sons, getting mathematical and astronomical facts from George, botanical facts from Francis, financial and mechanical help from the others. It seems to many a mistake that the President, Mr. Francis Darwin, who has written delightfully on his father's life, held aloof from evolution. A big popular audience was longing to hear what this satisfying word, which can be safely used in the drawing-room, really meant. The President is a good Darwinian, a firm believer in the adequacy of natural selection, recently much out of favour with men of Science. Instead he plunged almost without an introduction into very difficult questions of cell development. The gist of the lecture was as severely handled by botanical critics as by the popular audience. Yet the contribution was original, and the short summing-up of his last paragraphs as plain and direct as, may one say, the concluding sentences of those inexplicable rigmaroles which so often made an hour's prelude to the decisive climax of Cromwell's speeches. It seems to me certain (said the President), that in development we have an actual instance of habit. If this is so, somatic inheritance must be a vera causa. Nor does it seem impossible that memory should role the plasmic link which connects successive generations--the true miracle of the camel passing through the eye of a needle--since, as I have tried to show, the reactions of living things to their surroundings exhibit in the plainest way the universal presence of a mnemonic factor. We may fix our eyes on phylogeny and regard the living world as a great chain of forms, each of which has learned something of which its predecessors were ignorant; or we may attend rather to ontogeny, where the lessons learned become in part automatic. But we must remember that the distinction between phylogeny and ontogeny is an artificial one, and that routine and acquisition are blended in life. This is at any rate a plain challenge to Weissmann, and what follows is an equally plain defence of natural selection. The great engine of natural selection is taunted nowadays, as it was fifty years ago, with being merely a negative power. I venture to think that the mnemonic hypothesis of evolution makes a positive value of natural selection more obvious. If evolution is a process of drilling organisms into habits, the elimination of those that cannot learn is an integral part of the process, and is no less real because it is carded out by a self-acting system. It is surely a positive gain to the harmony of the universe that the discordant strings should break. As I listened to the slow and unemotional delivery of this interesting and unorthodox address, it occurred to me how differently it would have impressed the audience if they could have been reminded of a delightful passage in Charles Darwin's autobiography, edited by the speaker. The simplicity of it makes it one of the great documents of the world, and this said address appears in the light of it as an incomparably Darwinian product. The passage is this: In 1880 I published, with Frank's assistance, our Power of Movement in Plants. This was a tough bit of work. The book bears much the same relation to my little book on climbing plants which Cross Fertilisation did to the Fertilisation of Orchids; for in accordance with the principle of evolution it was impossible to account for climbing plants having been developed in so many widely different groups unless all kinds of plants possess some power of movement of an analogous kind. …
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