INDEX 



473 



Hensen, Victor, on amphigonic 

 heredity, 253; on the increase of 

 a character, 424 



Herbert, experiments with Cytisus 

 adamiy 343 



Hereditary substance, not contained 

 in the body of the cell, but in its 

 nucleus, 10; composed of primary 

 constituents, 15; forms but a 

 small part of the substance of the 

 egg, 22; composed of different 

 qualities, 26; the extreme com- 

 plexity of its structure, 29; its 

 growth, 31 ; of unicellular organ- 

 isms, 45 1; of multicellular organ- 

 isms, 452 



Heredity, its fundamental phenom- 

 ena, 20; in unicellular organ- 

 isms, 52; in reference to the 

 structure of the germ-plasm, 69; 

 homotopic and homochronic 

 forms, 75 ; in monogonic repro- 

 duction, 92; in sexual reproduc- 

 tion, 230, 253; explanation of 

 apparently monogonic heredity in 

 plant-hybrids, 259; in Man, 259; 

 as regards the colour of the eyes, 

 278; example of apparently mono- 

 gonic heredity, 267, 280; force 

 of, 290; as regards acquired 

 characters, 392 f mutilations, 396; 

 'sports,' 444; the apparatus for 

 transmission, 466 



Hertwig, Oscar, view of fertilisation 

 as a conjugation of nuclei, 23; 

 on the germinal layers of the 

 Metazoa, 113; on the nuclear 

 rods in two varieties of Ascaris 

 ■megalocephala, 241 



Heterobiophorids, hypothetical pri- 

 mitive organisms, 450 



Heterokinesis, nuclear division re- 

 sulting in parts which are dis- 

 similar as regards their hereditary 

 tendencies, 34 



Hildebrandt, hybrids of two species 

 of Oxalis, 255 



His, theory of special regions in the 

 germ giving rise to special organs, 



134 

 Hoffmann, experiments with Papa- 

 ver alpinum, 437 



Homobiophorids, hypothetical pri- 

 mitive organisms, 450 



Homoeokinesis, nuclear division re- 

 sulting in parts which are similar 

 as regards their hereditary ten- 

 dencies, 34 



Hoppe-Seyler, chemical constitu- 

 tion of protoplasm, 40 



Humming-birds, sexual dimorphism 

 of, 427 



Hybrids of various species of plants, 

 255; the theory of idants, 259; 

 plant - hybrids, 260 ; apparent 

 monogonic transmission in, 302 



Hydra, regeneration, 127; gemma- 

 tion, 155 



Hydractinia echinata, formation of 

 germ-cells, 189 



Hydroids, formation of the bud 

 from a single cell, 166; embryo- 

 geny, 184; shifting of place of 

 origin of germ-cells, 186; germ- 

 tracks of, 207 



Id, the, in ontogeny, 60; the num- 

 ber contained in the individual 

 idant, 241 



Idants, constituting the hereditary 

 substance in sexual reproduction, 

 234; composed of dissimilar ids, 

 238; constituting groups of ids, 

 241 ; their number, 245; become 

 doubled by division, 246; com- 

 bination of, 247; of ancestors 

 contained in the germ-plasm, 257 ; 

 their combination in plant-hybrids, 

 297, 302 ; intermingling of, in 

 transmission, 312 



Idioplasm, Nageli's conception of 

 the, 10; my view of the, 33; con- 

 trasted with morphoplasm, 38; 

 composed ot ids, 63 ; phyletic 

 variation of, in the differentiation 

 of species, 79, 434 



Ids or ancestral germ- plasms com- 

 posed of determinants, 62; their 

 individual difference, 236 ; homo- 

 logous and heterologous, 264; 

 gradual transformation of, 271; 

 number variable according to age 

 of characters, 273 ; struggle of 

 parental ids, 285 



