372 



INDEX 



Reverse mutations, 350-355 



Right and left-handedness, in twins, 



198, 255 

 Rotifera, 81 

 Rules of inheritance, 206-231 



Salamandra, 249 



Schofield, 128 



Schrader, F., 81 



Schultz, J., 333, 334, 339, 365 



Sea urchin hybrids, 266-272 



Secondary sex characters, 70-74; re- 

 lation to Y, 124-128; in sheep, 125; 

 in fish, 126-128 



Selection, results of, 230-231 



Selective action on germ cells, 76 



Sex, relation to chromosomes, 14-22, 

 55-75 ; two groups of organisms, 56, 

 96; relation to autosomes, 62-65; 

 development of sex differences, 68- 

 70; sex hormones, 74; determina- 

 tion by non-chromosomal methods, 

 75-81 ; diverse conditions as to sex 

 in different organisms, 80-81 ; ratio 

 of males to females, 76; transfor- 

 mation of one sex into another, 77; 

 environmental determination, 79 



Sex chromosomes, 54, 57, 81 



Sex determination, 14-20, 58-82; by 

 other methods than chromosomes, 

 75-81; environmental, 79; works 

 on, 81 



Sex-linked inheritance, 83-103, 129, 

 209; rules, 85-90; dominance and 

 recessiveness, 94; tests for, 95; two 

 groups, 96-97; in man, 98; in fruit- 

 fly, 99 



Sharp, L. W., 54 



Sheep, 125 



Shepherd's purse, 185, 222 



Shull, G. H., 205 



Siemens, H. W., 257, 265 



Similarity and relationship, 299 



Size, 226 



Snapdragon, 304 



Soil, effect on inherited characters, 246 



Spermatocyte, 47 



Spermatogonia, 47 



Sperms, sperm cell, 6, 51 ; death of 

 certain types, 76 



Sphaerechinus, 269-272 



Spireme, 43 



Squid, sex ratio, 76 



Stanford-Binet tests, 257-263 



Steggerda, M., 282 



Sterility, from absence of Y, 62; in 

 hybrids, 273-276 



Stockard, C. H., 278, 279, 282 



Stubbe, H., 365 



Sturtevant, A. H., 20, 22, 35 



Substitution of chromosomes, 13, 18, 

 22, 28 



Sunlight, efifect on inherited charac- 

 ters, 246 



Super-females, 62, 64 



Superiority, genetic, origin of, 293, 

 297, 302 



Super-males, 64 



Supplementing genes, 291-293, 302 



Swezy, O., 81 



Synapsis, 48 



Tammes, T., 229 



Tan, 99, 100 



Temperament (twins), 259-263 



Temperature, effect on inherited 



character, 243, 249; production of 



mutations, 348-350 

 Tennent, D. H., 270, 281 

 Testis, 70 



Tests for sex-linked inheritance, 95 

 Tetrads, 49, 50 



Tetraploids, 321, 323, 324, 325 

 Tetrasomics, 320 



Timofeef-Ressovsky, N. W., 354 

 Tobacco, 302-304 

 Transformation of organisms, 301- 



314 

 Translocations, 326, 328, 330-332 

 Trihybrid (dependent on 3 pairs), 



119 

 Triploids, 63, 321, 323, 325 

 Trisomies, 317-320, 323 

 Tschermak, A. v., 229 

 Twins, 198-204, 254-263; identical, 



198, 254-265; fraternal, 200, 254; 



physical characteristics, 200, 255; 



mental characteristics, 201-204, 257- 



264; moral characteristics, 202; 



criminality, 202 ; temperament, 263 ; 



emotion, 263 

 Types of inheritance, 129, 206 



Uniparental reproduction, 286, 308- 



310, 324 

 Unit character, 207, 210, 211 

 United X-chromosomes, 91 

 Unstable mutations, 350-355 



Variation greater in F2, 226-229 

 Variations, genetic, 288, 315-365 

 Variegated plants, 352-354 

 Vegetative reproduction, 286, 308-310, 

 324 



