accidental individual things, such as crystals or pieces of stone; and, lastly, there are living individuals which, as he pointed out, were cycles. All living things are born into the world, grow up, and die, and it was to the cycle of life, from the egg to the adult which produces eggs, that he gave the name individual. In a simple animal like Hydra there is no difficulty in accepting this plain definition of individuality; but Huxley went on to compare with Hydra a compound creature like the Portuguese man-of-war, which really is composed of a colony of Hydra-like creatures, the different members of the colony being more or less altered to serve different functions. All these have come from the branching of a single simple creature produced from an egg, and to the whole colony Huxley gave the name of zoölogical individual. The salps give a still wider interpretation to this view of individuality. The original salp produced from the egg gives rise to many salps, which may either remain attached in a chain, or, breaking away from one another, may live separately. Huxley extended the use of the word _individual_ so as to include as a single zoölogical individual the whole set of creatures cohering in chains or breaking apart, which had been produced by budding from the product of a single egg-cell. This subtle analysis of ideas delighted and interested his contemporaries, and the train of logical examination of what is meant by individuality has persisted to the present time. Like all other zoölogical ideas, this has been considerably altered by the conception of evolution. Zoölogists no longer attempt to stretch logical conceptions until they fit enormous and different parts of the living world. They recognise that the living world, because it is alive, is constantly changing, and that living things pass through different stages or kinds of individuality in the course of their lives. A single egg-cell is one kind, perhaps the simplest kind, of zoölogical individual; when it has grown up into a simple polyp it has passed into a second grade of individuality; when, by budding, the polyp has become branched, a third grade is reached, and when the branches have become different, in obedience to the different purposes which they are to serve in the whole compound creature, a still further grade is reached. Huxley's attempt to find a meaning for individuality that would apply equally to a single simple creature, to a compound creature, and to the large number of separate creatures, all developed by budding from one creature, is a striking instance of his singular capacity for bringing apparently dissimilar facts into harmony, by finding out the common underlying principle, and, although we no longer accept this particular conclusion, we cannot fail to notice in it the peculiar powers of his mind.