Cell, description of, 31; characters possible in, 88; differentiation of, in development, 112; as units in morphology and physiology, 113; Sachs on, 114; Vöchting on, 114, 116. Cell theory, relation of, to heredity, 31. Centrosome, an organ of cells most obvious during nuclear division, 93. Cerianthus, experimental heteromorphoses, 51. CHABRY, destruction of segmentation sphere, 62. Chromatin, a material found in the nucleus of cells, so called because it absorbs stains with avidity: germplasm and, viii, xiv; relation of, to specific character of cells, 36, 37. Chromosomes, definite, visible bodies, as which the chromatin of a dividing nucleus appears, xiv, 93. Crystal, growth of, compared with organic growth, 108. Cione, experimental heteromorphoses, 52. Clavellina, reproduction from buds, 46. Cleavage-planes, the planes separating the daughter-nuclei, or daughter-cells, in the early division of a fertilised egg-cell, xvii; relation between appearance of, and structure of eggs, 95. Coelenterata, a major division of multicellular animals, including such creatures as sea-anemones, corals, and jelly-fish, 46. Continuity of the germplasm, 26. Continuity of life, the doctrine opposed to spontaneous generation, 2. Correlations, 118, 121. D DARWIN, pangenesis, 21. Determinants. Each _id_ of germplasm is supposed by Weismann to be composed of minor pieces, arranged in a complicated fashion that is the result of the past history of the species. For every part of the body, large or small, that may be different in different individuals or species, there is, at least, one determinant in the _id_. The determinants are so grouped in the _id_ that they are liberated and become active when the time comes for the development of that part of the body they control, viii, 22; arguments against, 82; relation to cells, 87. Determinates, the smallest parts of an organism which vary independently, and which are supposed by Weismann to be represented in the germplasm by special pieces, 23, 25. Differentiating division, such a division of the nucleus as would result in daughter-nuclei unlike each other, and unlike the parent nucleus. The qualities of the parent nucleus are supposed to have been distributed between the daughter-nuclei, xi; absence of visible evidence for, xv, 25; objections to occurrence of, 34, 78. Dimorphism, the appearance of the same species in two different forms, sexual dimorphism, 122, 124. Disharmonic union in grafting, 70. Double monsters, as examples of heteromorphosis, 63. Doubling division. When an amoeba reproduces by simple division, the daughter-amoebæ are identical, and each is identical with the parent except in size; from one amoeba two have been formed. A doubling division of the nucleus is such as would result in the formation of two nuclei alike in every respect, ix; visible evidence for, xv, 24; in unicellular organisms, 40; occurrence of, with differentiating division, 78.