Chapter 4 No.4

Ids, hypothetical individual pieces, a number of which are supposed by Weismann to be present in the germplasm of every sexual cell, and each of which is supposed to contain the inherited material necessary for a complete new organism. It has been suggested that tiny beads seen within the chromosomes of a sexual cell are the ids, viii, 23, 33.

Idioblasts, Hertwig's name for hypothetical ultimate units of living matter, 22, 82;

the ultimate units of living matter, according to De Vries, 22.

Idioplasm, as opposed to germplasm, which is the nuclear material of germ-cells; idioplasm is the nuclear material of tissue-cells, xi, 38.

Immortality, definition of, 82;

of germ-cells, ix;

of unicellular organisms, 17;

of germ-cells, 80.

Individuality of cells, 115.

Invagination, the infolding of a layer of cells, as, for instance, in the transformation of a blastosphere into a gastrula, xvii.

Isotropism, explained in footnote, 33.

K

Karyokinesis, a complicated process of nuclear division, xiv.

Katabolism, the formation of less complex chemical bodies by the agency of protoplasm, 86.