by him, in common with most other thinkers of his period, is still held more or less unconsciously by those who have not given particular attention to the subject. Generation is conceived as a direct chain: the body produces the germ-cell which produces another body which in turn produces another germ-cell, and so on.
But a generation ago this idea fell under suspicion. August Weismann, professor of zoölogy in the University of Freiburg, Germany, made himself the champion of the new idea, about 1885, and developed it so effectively that it is now a part of the creed of nearly every biologist.
Weismann caused a general abandonment of the idea that the germ-cell is produced by the body in each generation, and popularized the conception of the germ-cell as a product of a stream of undifferentiated germ-plasm, not only continuous but (potentially at least) immortal. The body does not produce the germ-cells, he pointed out; instead, the germ-cells produce the body.