The title of the author presidential address, people will have discerned, is ‘A Biological Retrospect’, and on the whole it has not been well received. Most people feel more confident in denying that certain things will come to pass than in declaring that they can happen or surely will happen. Many a golden opportunity to remain silent has been squandered by anti-prophets who do not realize that the grounds for declaring something impossible or inconceivable may be undermined by new ideas that cannot be foreseen. J. S. Haldane is very critical of the theories of memory propounded by Ewald Hering and Richard Semon, who assume that memory in general is dependent on protoplasmic “engrams”, and that germ-cells are furnished with a system of engrams, functioning as guide-posts to all the normal stages of development. The dynastic conception coloured our thoughts long after the revival of Darwinism had made it altogether inappropriate.