INDEX 



549 



Thompson, cross of yellow X 



green peas, 235 

 diagram of Galton's 1st 



Law, 222 

 Thomsen's disease, 303 

 Thorndike, behavior of dogs, 



cats, monkeys, 69 

 "Thoroughbreds," 430 

 Thymus gland, fed to tadpoles, 



334 

 Thyroid, effects on development, 



339 

 gland, fed to tadpoles, 334 

 Totipotence, of cleavage cells, 



324, 326, 341 

 Tower, action of selection, 387 

 mutations in Leptinotarsa, 



318, 357, 401 

 Toxopneustes, fertilization of 



egg, 20 

 Traducianism, 44 

 Training of animals, 74 

 Transmission hypothesis, 97 

 Trial and Error, 68 

 Trihybrid, 249, 250, 392 

 Triplets, hereditary, 210 

 Trophic correlations, 337 

 Tropisms, 56-60 

 Tschermak, rediscovery of 



"Mendel's Law," 230 

 Tuberculosis, inheritance of, 



207, 208 

 Turbellarian type of egg, 182 

 Twins, fraternal, 332 

 hereditary, 210 

 identical, 219, 331, 367, 474 



Ultra-microscopic units, 105 

 Uniqueness of every individual, 



161, 218-220 

 Unit Characters, 257, 259 

 Units of living matter, 103-108 

 ultra microscopic, 105 

 units of growth and division, 

 105 



units of heredity, 105-108, 

 259-271 

 Unity of organism, 49 

 Universal laws, 467 

 Use and disuse, effects of, 335 



effects not inherited, 343 

 Uterus, attachment of oosperm 

 to, 34 



Variability, caused by environ- 

 ment, 400 

 Variations, continuous, 216 



discontinuous, 216 



fluctuations, 217, 218 



meristic, 216 



mutationj, 215, 217 



"sports," 216 

 Varied responses, 74 

 Vegetative pole of egg, 174 

 Viviparity, 32 

 Viviparous development, 18, 19 



Walter, diagram of Galtonian 

 inheritance, 214 

 filial regression, 226 

 Wars, effects of, 438, 439 



shake off social heredity, 

 372 

 Wassermann test, 160 

 Watase, symmetry of egg of 



Loligo, 175 

 Weeks, 212 

 Weidal test, 160 

 Weismann, determinants and 

 biophores, 106, 261 

 germ plasm theory, 101, 344 

 hereditary and environment- 

 al variations, 218 

 on differential division of 



chromosomes, 131 

 inheritance of acquired 



characters, 343 

 nuclear control of differ- 

 entiation, 187 



