Let us go on admitting and continue. The desired point is struck; the prey is duly paralysed; the egg laid on its flank will develop in safety. Is that enough? It is at most but a half of what is absolutely necessary. Another egg is indispensable to complete the future couple and ensure offspring. Therefore, within a few days’, within a few hours’ interval, a second sting must be given, as successful as the first. In other words, the impossible has to be repeated, the impossible raised to the second degree. Let us not be discouraged yet; let us sound the uttermost depths of the problem. Here is a Wasp, some precursor, no matter which, of our Ammophila, who, favoured by chance, has twice and perhaps oftener succeeded in reducing the prey to that state of inertia which the rearing of the egg imperatively demands. She does not know, does not suspect that she inserted her sting opposite a nerve-centre rather than elsewhere. As there was nothing to prompt her choice, she acted at random. Nevertheless, if we are to take the theory of instinct seriously, we shall have to admit that this fortuitous action, though a matter of indifference to the insect, left a lasting trace and made so great an impression that, henceforth, the cunning stratagem which produces paralysis by attacking the nervous centres is transmissible by heredity. The Ammophila’s successors, by some prodigious privilege, will inherit what the mother did not possess. They will know by instinct the point or points towards which the sting must be directed; for, if they were still in the prentice stage, if they and their successors had to risk the chance that accident would tend gradually to strengthen the nascent impulse, they would be going back to the likelihood so near allied to nil; they would go back to it year by year, for centuries to come; and yet the one and only favourable chance would have to be always recurring. I find it very difficult to believe in a habit acquired by this prolonged repetition of incidents whereof not one can take place without excluding so many contrary chances. It is a simple matter of arithmetic to show the number of absurdities against which the theorists rush headlong.