Keimplasma

"NOW that the conception of the germ-plasm as the hereditary substance contained in the germ-cells has been fully established, and since it has been shown in general terms that this form of the idioplasm must become changed during ontogeny and converted into the idioplasm of the cells which constitute the mature organism, we must attempt to form some idea of its nature; for it would otherwise be impossible to construct a theory of heredity."