Idioplasm

That part of the protoplasm which carries the hereditary powers and governs development; now ascertained to be lodged in the chromatin of the cell nucleus or nucleolus. The original idioplasm of Nägel i was conceived as a structural system of micellæ in the protoplasmic threads of the cell reticulum. A cro -section of such a thread was supposed to give all the sorts of micellæ present in the cell, growth taking place longitudinally. Cell division alone affects the structure of the cro -section by a splitting of the fibril. Every species has presumably a different structure of the idioplasm, and development is explained as a succe ive activity of different rows of micellæ, much as the gemmules of the pangenesis theory become succe ively active.