I. Haeckel and His Opponents

We find ourselves once more in face of a doctrine of Chinese boxes one within another. Weismann conceives of the progressive process through which the germs bring about evolution, as a material process. When an organism develops, one portion of the germ-mass out of which it evolves is solely employed in forming a fresh germ for the sake of further reproduction. In the germ-mass of a descendant, therefore, a part of that of the parents is present, in the germ-mass of the parents a portion of that of the grandparents, and so on backwards to the root-form. Hence through all organisms developing one from another there is maintained an originally present germ-substance. This is Weismann's theory of the continuity and immortality of the germ-plasm. He believes himself to be forced to this view, because numerous facts appear to him to contradict the assumption of the inheritance of acquired characteristics. As one specially noteworthy fact he cites the presence of the workers, who are incapable of reproduction, among the communal insects—bees, ants, and termites. These workers are not developed from special eggs, but from the same as those from which spring the fruitful individuals. If the female larvae of these animals are very richly and nourishingly fed, they then lay eggs from which queens or males proceed. If the feeding is less generous, the result is the production of sterile workers. Now, it is very easy and obvious to seek the cause of this unfruitfulness simply in the less effective nourishment.