Undoubtedly the theory of descent with modification, which received its first sufficiently ample and undisguised exposition in 1809 with the “Philosophie Zoologique” of Lamarck, shared the common fate of all theories that revolutionise opinion on important matters, and was fiercely opposed by the Huxleys, Romaneses, Grant Allens, and Ray Lankesters of its time. It had to face the reaction in favour of the Church which began in the days of the First Empire, as a natural consequence of the horrors of the Revolution; it had to face the social influence and then almost Darwinian reputation of Cuvier, whom Lamarck could not, or would not, square; it was put forward by one who was old, poor, and ere long blind. What theory could do more than just keep itself alive under conditions so unfavourable? Even under the most favourable conditions descent with modification would have been a hard plant to rear, but, as things were, the wonder is that it was not killed outright at once. We all know how large a share social influences have in deciding what kind of reception a book or theory is to meet with; true, these influences are not permanent, but at first they are almost irresistible; in reality it was not the theory of descent that was matched against that of fixity, but Lamarck against Cuvier; who can be surprised that Cuvier for a time should have had the best of it? And yet it is pleasant to reflect that his triumph was not, as triumphs go, long lived. How is Cuvier best known now? As one who missed a great opportunity; as one who was great in small things, and stubbornly small in great ones. Lamarck died in 1831; in 1861 descent with modification was almost universally accepted by those most competent to form an opinion. This result was by no means so exclusively due to Mr. Darwin’s “Origin of Species” as is commonly believed. During the thirty years that followed 1831 Lamarck’s opinions made more way than Darwinians are willing to allow. Granted that in 1861 the theory was generally accepted under the name of Darwin, not under that of Lamarck, still it was Lamarck and not Darwin that was being accepted; it was descent, not descent with modification by means of natural selection from among fortuitous variations, that we carried away with us from the “Origin of Species.” The thing triumphed whether the name was lost or not. I need not waste the reader’s time by showing further how little weight he need attach to the fact that Lamarckism was not immediately received with open arms by an admiring public. The theory of descent has become accepted as rapidly, if I am not mistaken, as the Copernican theory, or as Newton’s theory of gravitation.