Index 





Sex glands, effects on development, 



224 



Sex hormones, 167 



Sex-limited inheritance, 73, 168 



Sex-linked inheritance, 73, 118, 



181-186 

 Sex ratio, modification of, 164-166 

 Scxnal reproduction, value of, 171 

 Share of egg and sperm in heredity, 



194, 197 

 Share of chromosomes and cyto- 

 plasm, 198 

 Shull, leaf colors, 112 



heterozygous, 261 

 Significance of cleavage, 144, 148, 201 



of mitosis, 131, 144, 148 

 Simplex character, 97 

 Skin color, 108 



mulatto, 108, 109 



influence of light on, 206 

 Slow breeding of man, 115, 296 

 Sobotta, fertilization of mouse, 139 

 Social inheritance vs. germinal, 242 

 Social institutions, deal only with en- 



vironmen, 242 

 Society, highest grade of organiza- 

 tion, 321 



power of, 279 



responsibility of, 321 



supreme duty of, 322-324 

 Soil, poor, induction effect on plants, 



235 

 Somatic discontinuity, 125 

 Somatoplasm, in cell body, 127 

 Sparta, destruction of unfit, 276 

 Special senses, origin of, 38 

 Specialized types, 282 

 Specificity of Germ Cells, 169, 174 



of protoplasm, 170 

 Spencer, physiological units, 129 

 • Sperm centrosome, 136 

 Sperm nucleus, 11, 21 

 Spermatocytes, 148 

 Spermatogenesis of Ancyracanthus, 



Spermatogonia, 148 

 Spermatozoon, 9, 11, 12 



formation of, 156 

 Spina bifida, 221 

 Spinal cord, development, 23 

 Spindle, mitotic, 17, 18, 138 

 Spirilla, reactions to chemicals, 39 



"Sports," 74 



Star-fish, isolated cleavage cells, 213 



Statistical methods rs. Physiological, 

 79. 80 



Statistical Study of Inheritani i. 

 76-81 



Stature, inheritance of, 66, 78, 79 

 tendency to mediocrity, 78 

 influence of food on, 206 



Stentor, modifiable behavior, 50 



Sterile insects, 297 



Sterility, 278, 293, 296 



Sterilization, 285 



Stevens, on sex determination, 759 



Stimuli, chemical and physical, 209, 



313 

 conflicting, 50 

 definition, 50, 208 

 Developmental, 208 

 non-specific, 209 

 external and internal, 50, 312 

 range of, 313 



rational, social, ethical, 312 

 summation of, 43 . 

 Stockard, alcohol on guinea-pigs, 

 210, 211, 2,12 

 experimental cyclopia, 169, 221, 

 222 

 Strasburger, phototropism of seed- 

 ling, 41 

 Structures and functions, reciprocal 



relations, 31, 35, 68 

 Stvela, anterior half-embryos, 217 

 dislocated organs, 219 

 egg substances, 140 

 gastrulation and larva, 147 

 half and three-quarter embryos, 



216 

 maturation, fertilization and 



cleavage, 143, 146, 147 

 posterior half-embryos, 218 

 Sumner, effect of cold on mice, 236 

 Superman, 280, 281, 296 

 Sweden, extinct noble families, 293 

 Swine, wild and domestic, 2$2 

 Symmetry, 190, 191 

 Synapsis, 150 

 Syndactylism, 69, 117 



Tadpoles, fed on thyroid, thymus, 

 adrenal, 2_»i 



