In its earlier stages the embryo should be simply conscious of a general method of procedure on the part of its forefathers, and should, by reason of long practice, compress tedious and complicated histories into a very narrow compass, remembering no single performance in particular. For we observe this in nature, both as regards the sleight-of-hand which practice gives to those who are thoroughly familiar with their business, and also as regards the fusion of remoter memories into a general residuum. II. We should expect to find that the offspring, whether in its embryonic condition, or in any stage of development till it has reached maturity, should adopt nearly the same order in going through all its various stages. There should be such slight variations as are inseparable from the repetition of any performance by a living being (as contrasted with a machine), but no more. And this is what actually happens. A man may cut his wisdom-teeth a little later than he gets his beard and whiskers, or a little earlier; but on the whole, he adheres to his usual order, and is completely set off his balance, and upset in his performance, if that order be interfered with suddenly. It is, however, likely that gradual modifications of order have been made and then adhered to. After any animal has reached the period at which it ordinarily begins to continue its race, we should expect that it should show little further power of development, or, at any rate, that few great changes of structure or fresh features should appear; for we cannot suppose offspring to remember anything that happens to the parent subsequently to the parent’s ceasing to contain the offspring within itself; from the average age, therefore, of reproduction, offspring would cease to have any further experience on which to fall back, and would thus continue to make the best use of what it already knew, till memory failing either in one part or another, the organism would begin to decay. To this cause must be referred the phenomena of old age, which interesting subject I am unable to pursue within the limits of this volume. Those creatures who are longest in reaching maturity might be expected also to be the longest lived; I am not certain, however, how far what is called alternate generation militates against this view, but I do not think it does so seriously. Lateness of marriage, provided the constitution of the individuals marrying is in no respect impaired, should also tend to longevity.