INDEX 



473 



Hensen, Victor, on amphigonic 

 heredity, 253; on the increase of 

 a character, 424 



Herbert, experiments with Cy/isiis 

 adami, 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, 451 ; 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 monogenic 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; 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 arc dis- 

 similar as regards their hereditary 

 tendencies, 34 



Hildebrandt, hybrids of two species 

 of Ox a lis, 255 



His, theory of special regions in the 

 germ giving rise to special organs, 



'34 

 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 



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

 ber contained in the individual 

 idant, 241 



Idants, constituting the hereditary 

 suljstance 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, lO; my view of the, 33; con- 

 trasted with morphoplasm, 38; 

 composed ol ids, 63 ; ])hyletic 

 variation of, in the diflcrentiation 

 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 



