INDEX 



667 



Telephone, 548 



Telophase, 289 (fig.) 



Temperature, 109, 139; as a bar- 

 rier, 455; of the sea, 483; as a 

 stimulus, 135; sense, 140 



Tendrils, 113 



Theory, cell, 15; of death, Weis- 

 mann's, 252; Darwin's, factors 

 of, 421 



Theories of evolution, 420 



Thermal rays, 39 



Thermotropism, 112 



Thigmotropism, 113 



Thirst, 137 



Thread worms, 200 (fig.), 208 



Thumb, flexibiUty of, 534 



Thyroid gland, hormone of, 172 

 (fig.); over-activity of, 184; 

 under-activity of, 182 (fig.) 



Thyroxin, 173, 183 



Ticks and disease, 244 



Tillage, 205 



Tissues, 32 



Toadstools, 210 



Tonsils, infected, 222 



Touch, 139; in relation to sight, 146 



Toxin, 232, 268 



Tracheal system of insects, 101 



(fig.) 



Traits, human, 505 



Transpiration, 60 



Transportation, 549; system, flat- 

 worm, 85 (fig.); systems, mod- 

 erately complex, 86 (fig.) 



Treatment of disease in plants, 

 213 



Treviranus, Gottfried, 14 



Triple fusion, 339 



Tropisms, mechanisms of, 117; of 

 roots, 112 



Trypsin, 94 



Tschermak, E. v., 351 



Tubercule, bacteria, 276; root, 212, 

 276 



Tuberculosis, 220 



Tubes, pollen, 338 



Turgor, 61 



Twins, resemblance of, 518 



Type, Alpine, 502; Mediterranean, 

 502; Nordic, 502; vegetation, 

 452 



Types of reproduction, 316 



Typhoid fever, 221; and flies, 

 237 



Ulothrix, 320 (fig.), 324 (fig.) 

 Unicellular animals, fertilization of, 



301; immortality of, 254; and 



bottom deposits, 487 

 Unsuitable environment, 204 

 Urea, 266, 272 

 Ureases, 68 

 Utihzation of food, 73 



Vaccination, 233 



Vacuole, 21 (fig.); contractile, 26 

 (fig.), 103 



Variability in inheritance, 516 



Variation, 349, 424, in carbon di- 

 oxid, 42; quantitative, 505 



Variety, 413 



Vegetation types, 452; of the 

 United States, 457 



Vegetative reproduction, 345 



Vertebrates, development of, 304 

 (fig.), 416 



Vessels, lymphatic, 89 (fig.) 



Vestigial organs, 414 



Vinegar fly, see Drosophila 



Virulence, 227 



Virus, disease due to, 225; filter- 

 able, 220 



Vitamins, 91, 188; deficiency in, 

 182 



Voice production, 133 



Vohtion, 163, 186, 540 



Volitional activity, 162 



Voluntary acts, 162 



Volvox, 28 (fig.) 



Von Bayer's hypothesis of photo- 

 synthesis, 43 



War, 546 



Warm-blooded animals, 79, 140 



Warning coloration, 443 



Waste, 81; animal, 272; decompo- 

 sition of nitrogenous, 266; dis- 

 posal of organic, 259; in func- 

 tional metabolism, 81 ; in growth 

 metabolism, 80; solid nitroge- 

 nous, 267 



Water, 38; contamination of, 235; 

 movement of, in roots, 56; front- 

 age, 83 



Weeds, sea, 272 



Weight of man, 511 



Weismann's theory of death, 252 



Whale, convergent adaptations in 

 the, 431 



