“But the machines which reproduce machinery do not reproduce machines after their own kind. A thimble may be made by machinery, but it was not made by, neither will it ever make, a thimble. Here, again, if we turn to nature we shall find abundance of analogies which will teach us that a reproductive system may be in full force without the thing produced being of the same kind as that which produced it. Very few creatures reproduce after their own kind; they reproduce something which has the potentiality of becoming that which their parents were. Thus the butterfly lays an egg, which egg can become a caterpillar, which caterpillar can become a chrysalis, which chrysalis can become a butterfly; and though I freely grant that the machines cannot be said to have more than the germ of a true reproductive system at present, have we not just seen that they have only recently obtained the germs of a mouth and stomach? And may not some stride be made in the direction of true reproduction which shall be as great as that which has been recently taken in the direction of true feeding? “It is possible that the system when developed may be in many cases a vicarious thing. Certain classes of machines may be alone fertile, while the rest discharge other functions in the mechanical system, just as the great majority of ants and bees have nothing to do with the continuation of their species, but get food and store it, without thought of breeding. One cannot expect the parallel to be complete or nearly so; certainly not now, and probably never; but is there not enough analogy existing at the present moment, to make us feel seriously uneasy about the future, and to render it our duty to check the evil while we can still do so? Machines can within certain limits beget machines of any class, no matter how different to themselves. Every class of machines will probably have its special mechanical breeders, and all the higher ones will owe their existence to a large number of parents and not to two only.