SUBJECT INDEX. 



413 



Sinapis alba, effect of light on 

 growth of, 245 



Skew curves of distribution, 29, 

 34 



Skull capacity, of rabbit, 332 



Snail, upon, relative growth of, 

 302, 303, 307; variation in, 

 314, 315; periodic selection in, 

 345 



Soma, effect of environment on, 

 223 



Somatic modifications, 223, 242, 

 244 



Somatic variations, influence of, 

 on germ-plasm, 360; impor- 

 tance of, 366, 390; adaptiveness 

 of, 389 



Somatogenic variations, 101, 223, 

 242, 244; laws governing, 189 



Sparrow, variability of English 

 and American, 212; natural 

 selection in, 341 



Species, and varieties, differ- 

 entiation of, 41; a precise 

 criterion of, 44; origin of, by 

 mutation, 59; produced by 

 hybridisation, 164 



Specific Gravity of waters, effect 

 of, on Artemia, 272; on Tubu- 

 laria, 278 



Specific metabolism, in animals, 

 296, 298, 309 



Sphcerechinus granularis, dimin- 

 ished fertility between varie- 

 ties of, 71 



Spines, development of, in plants, 

 263; produced by natural 

 selection, 391 



Sports, arising in CEnothera 

 Lamarckiana, 61; nature of, 

 170; stability of, 170; among 

 Lepidoptera, 171; prepotency 

 of, 171; among sheep, 172; 

 among peacocks, 172; obey 

 Law of Heredity, 172; pro- 

 duction of, 173; artificial pro- 

 duction of, in Lepidoptera, 

 175; among Lepidoptera, 237 



Squirrels, variation in, 329 



Stability, organic, position of 

 170 



Staleness of sex-cells, effect of, 

 on development, 105, 107 



Standard Deviation, defined, 26 



Statistical methods, 36 



Stature, of parents and children, 

 130; of school Children, 202; 

 human, variability of, 205 



Stems, interchange of, with roots, 

 376 



Sterility, between varieties, 69; 

 between races of men, 70; of 

 atypical forms, 89, 90; pro- 

 duced by changed conditions 

 of life, 94 



Sterna hirundo, variation of, 7 



Sternum, diminished by disuse, 

 333 



Strongylocentrotus lividus larvae, 

 measurements of, 14; figures 

 of, 105; reaction of, to temper- 

 ature, 193, 194; effect of en- 

 vironment, on variability of, 

 217 



Substantive variations, 53 



Subterranean caves, animals in, 

 254 



Sunlight, effect of, on growth of 

 plants, 246 



Surroundings, effect of, on vari- 

 ability, 218, 220; effect of, on 

 growth, 189; adaptation to 

 changed, 390 



Swine, variation in Mullerian 

 glands of, 25 



Tadpoles, development of, in 

 relation to temperature, 225; 

 effects of feeding on, 292; 

 acclimatisation of, to tempera- 

 ture, 385 



Telegony, in mare, 175; negative 

 results regarding, 176; statisti- 

 cal examination of, 176 



Temperature, effect of, on growth 

 of Echinoderm larvae, 190, 

 194, 196; variable effect of, 

 on growth, 196; diminishing 

 effect of, with development, 

 197; fatal, on developing 



