INDEX 



401 



Light, change of intensity on plants 

 (Darwin), 19; graded by means of 

 prism, 39, 60; pressure of, and 

 supposed effect on orientation, 43; 

 graded by means of lens, 60, 61; 

 effect of constant, and change of 

 intensity of, on reactions of: 

 Euglena, 16, 83, 85, 98, 99, 100- 

 112, Stentor, 113-115, 118-123, 

 Swarm-spores, 127, Trachelomo- 

 nas, 130, Chlamydomonas, 132, 

 133, Volvox, 139, 143-145, Eudo- 

 rina and Pandorina, 147, Hydra, 

 157, Eudendrium, 161, 163, Me- 

 dusae, 165, Arenicola larvae, 172- 

 175, Fly larvae, 191-197, earth- 

 worms, 204, Planaria, 208, 210, 

 general, 229-235, 241, 245, 253- 

 258, 299, 366, 367; effect of, on 

 movement, 245; reactions to sud- 

 den decrease of, 247-250; reac- 

 tions to sudden increase of, 250, 

 251; reactions to continued illumi- 

 nation, 252, 253; effect of, on 

 reversal in reactions, 265-272, 

 299; characteristics of, 303; effect 

 of, on chemical reactions, 308-312. 



Light grader, 60-62. , 



Lillie, 166. 



Limax, 265. 



Limnaeus stagnalis, 345. 



Limnea columella, 214. 



Limuluspolyphemus,larvaeof, orien- 

 tation in light from two sources, 

 87; 88; 258; 271; reversal in reac- 

 tions, 285; 346. 



Lineus ruber, 284; effect of color on 

 reactions, 355. 



Littorina, aggregation of, 244; 247; 

 periodic movements caused by 

 tides, 286. 



Lobster larvae, orientation and 

 change in sense of orientation, 

 226, 264; 267. 



Loeb, 11; 17; 21; object of observa- 

 tions on reactions of animals, 23, 

 24, 34; control of movement in 

 animals and plants identical, 25, 



26, 164, 346; on relation between 

 sensations and animal behavior, 



27, 28; first theory of orientation 

 (ray direction), 24, 25, 34; second 

 theory of orientation (angle of 

 rays), 28, 29, 35; third theory of 

 orientation (intensity difference), 

 29-31, 35, 221; effect of constant 

 intensity compared with change 

 of intensity, 32, 33; extent of 

 appHcation of theories, 33, 34; 

 ideas on animal behavior sum- 

 marized, 34-36; theory of orien- 

 tation (tropism) compared with 

 Verworn's, 39; 40; 42; 52; 53) 

 definition of tropism, 54-58; 70; 

 80; 83; 86; theories criticized. See 

 Criticism; theories of orientation 

 applied to: Volvox, 137, 144, 146, 

 Hydra, 149, 150, 159, Arenicola 

 larvae, 173, earthworms, 205, Pla- 

 naria, 209, Caprella, 225, ants, 

 351; 363; 364; on orientation in 

 Eudendrium, 164; 168; 171; orien- 

 tation in Musca larvae, 175, 176, 

 182, 183; 177; 178; 180; 192; 194; 

 198; reactions of planarians to 

 light, 206; on circus movements, 

 215; 216; 220; 223; 229; 230; 

 234; 238; on origin of reactions, 

 239-243; cause of aggregation in 

 Planaria, 245; 247; heliotrppism 

 compared with Unterschiedsemp- 

 findlichkeit, 254-257; 258; on 

 adaptation and change in sense 

 of reaction, 266, 267, 272, 273, 

 285; effect of chemicals on reac- 

 tions, 279; effect of concentration 

 of medium on reactions, 283; 284; 

 effect of different colors on reac- 



