290 MEMORIES OF MY LIFE
more fully gone into here ; I must refer to the Memoir, itself. The general result of the inquiry was to support the views of those who hold that man is little more than a conscious machine, the slave of heredity and environment, the larger part, perhaps all, of whose actions are therefore predictable. As regards such residuum as may not be automatic but creative, and which a Being, however wise and well-informed, could not possibly foresee, I have nothing to say, but I found that the more carefully I inquired, whether it was into hereditary similarities of conduct, into the life-histories of twins, or introspectively into the actions of my own mind, the smaller seemed the room left for this possible residuum.
Many possibilities suggested themselves after reading Darwin's " Provisional theory of Pangenesis." One was that the breed of a race might be sensibly affected by the transfusion of blood from another variety. According to Darwin's theory, every element of the body throws off gemmules, each of which can reproduce itself, and a combination of these gemmules forms a sexual element. I f so, I argued, the blood which conveys these gemmules to the places where they are developed, whether to repair an injured part or to the sexual organs, must be full of them. They would presumably live in the blood for a considerable time. Therefore, if the blood of an animal of one species were largely replaced by that of another, some effect ought to be produced on its subsequent offspring. For example, the dash of bull-dog tenacity that is now given to a breed of greyhounds by a single cross with a bull-dog, the first generation cor-
