INDEX 



409 



Vanessa antiopa, 216; reactions to 

 light, 227; aggregation of, 244; 

 260. 



Variability, in reactions, 264-301; 

 367; chemical regulation of, 370. 

 See Modifiahility. 



Vaucheria, 31; 265. 



Vermes, aggregation, 242. See 

 Earthworm. 



Vertebrates, 233. 



Verworn, 11; 35; theory of orienta- 

 tion (tropism), 36-38; same com- 

 pared with Loeb's theory, 38, 39; 

 general application of theory, 39; 

 42; 52; 53; definition of tropism, 

 55; 56; 57; 70; 80; 104; 112; 113; 

 122; 168; 171; theory of orienta- 

 tion applied to: Arenicola larvae, 

 173, earthworms, 205; 229; 234; 

 265; on effect of different colors 

 on reactions, 303; reactions of 

 unicellular forms in spectrum, 326, 

 327. See Criticism. 



Vicia sativa, 315, 316. 



Vierordt, brightness in spectrum, 



305-307- 

 Vision, as a factor in orientation, 



218, 219, 223, 224, 233; color: 

 in Daphnia, 339,'' in ants, 350, in 

 bees, 354, in fishes, 358-360, in 

 birds, 360, in monkeys, 360, in rac- 

 coon, 360, in dancing mouse, 360, 

 in general, 364, 365. 



Visual purple, 307. 



Vitalism, origin and early ideas on, 

 8; 52; theory of (Driesch), 374- 



378. 



Vitis, 265. 



Voechting, 71. 



Volvox, Oltmann's experiments on, 

 39; orientation in light from two 

 sources, 87; rate of movement in 

 dififerent intensities of light, 100, 

 loi; function of eye-spots, 109; 



structure of, 136; locomotion, 136; 

 distributionof sensitive tissue, 137; 

 mechanics of orientation, 137-144, 

 231; orientation of segments, 142, 

 143; orientation in negative col- 

 onies, 143; change in sense of ori- 

 entation, 145, 267-270, 280, 287, 

 299, 300; orientation in light com- 

 pared with orientation in a gal- 

 vanic current, 145, 146; 148; 

 orientation compared with that in 

 Arenicola larvae, 169, 171; adap- 

 tation, 236; aggregation of, 242; 

 255; 257; 259; 263; 265; change 

 in sensitiveness and optimum, 

 289-292, 301; 367; 370; 374. 



Wager, eye-spot in Euglena, 81, 82, 

 106. 



Walter, definition of tropism, 55; 

 reactions of Planaria, 207, 245. 



Washburn, definition of tropism, 56; 

 on movement in Hydra, 150; 

 211. 



Washburn and Bentley, color vision 

 in fishes, 358, 359. 



Wasps, modification in reactions of, 

 296, 297. 



Watson, 360. 



Weber, 9; law of, 363, 



Wheeler, definition of tropism, 56. 



Whitman, reactions of Clepsine to 

 shadows, 249. 



Wiesner, 19; 60; 265; effect of differ- 

 ent rays on reactions of plants, 

 310, 314-3171 322, 362. 



Willow borer, adaptation in cater- 

 pillar of, 238. 



Wilson, reactions of Hydra to light, 

 150; 265; effect of different rays 

 on reactions of Hydra, 310, 362; 

 reactions of Hydra in spectrum, 



333-335- 

 Wohler, 9. 



