INDEX 



405 



Polygordius larvae, 266; reversal in 

 sense of reaction, 273, 279, 283, 

 300; 346. 



Porter, 360. 



Porthesia chrysorrhoea, 31; 336; 346; 



371- 

 Potamilla oculifera, 247. 



Pouchet, 247. 



Pouillet. Sec Dutrochet. 



Prawns, 249; 257; 260, 



Preference method, 10; 343. 



Preyer, 10. 



Pringsheim, protoplasmic streaming, 



75- 

 Problems, in reactions to light, 



statement of, i, 2, 3, 57, 58. 

 Protozoa, 51. See Table oj Contents. 

 Protula intestimum, 247. 

 Psychic phenomena, in organisms, 



9, 10, 27; in Euglena, 102; in frogs 



and toads, 223, in ants, 350, in 



bees, 353. 

 Psychoid, defined, 377. 

 Purkinje's phenomenon, 305. 



Raccoon, color vision, 360. 



Radl, theory of orientation (pres- 

 sure of hght), 42, 43; cause of 

 change in sense of orientation, 

 43; definition of tropism, 55; 214; 

 on circus movements, 216, 217; 

 234; 264; 265. 



Rana, 260; 273. 



Ranatra, 217; 218; 226; 260; reversal 

 in reactions, 271, 273, 280, 284, 

 300; modification in reactions of, 

 296; 367. 



Raphanus, 314. 



Rawitz, 247. 



Ray, explanation of movement in 

 plants, 7; orientation in plants, 12. 



Ray direction, as used by Sachs, 14; 

 effect of, on orientation in animals 

 (Loeb), 24-26; compared with dif- 



ference of intensity, 27; Oltmanns 

 on, 39, 40; function of, in orienta- 

 tion: plumules, 68, 69, Euglena, 

 83, 87, no. III, Stentor, 114, 118, 

 Hydra, 150, Musca larvae, 180- 

 182; 137; 144; 241; Davenport on, 

 254-256. 



Reactions to light, distribution of, i; 

 preference method, 10; problems in, 

 i~3> 57? 585 ill various organisms. 

 See Table of Contents; classification 

 of, 253-256; reclassification of, 256- 

 262; evolution of, 262, 263. 



Reactions, to shadows, 247-250; to 

 sudden increase of light intensity, 

 250, 251; to continued illumina- 

 tion, 252, 253, 257; to change of 

 intensity, 257; of questionable 

 cause, 258; caused by direct effect 

 of light, 258; caused by indirect 

 effect, 258-260; caused by what 

 light represents, 260; fundamental 

 cause of, 258-260, 278, 279, 298, 

 300, 320, 363, 366; reversal in, 

 264-267, 355; cause of reversal in, 

 267-287, 299; extent of reversal 

 in, 271; effect of light on reversal 

 in, 265-272, 299; effect of tem- 

 perature on reversal in, 272-279, 

 300; effect of chemicals on re- 

 versal in, 279-283, 300; effect of 

 concentration of medium and me- 

 chanical stimuh on reversal in, 

 283, 284, 300; effect of internal 

 changes on reversal in, 284-287; 

 variability and modifiability in: 

 general, 288-297, 361, 362, in ants, 

 351, in bees, 352-354, in higher 

 Crustacea, 355-358, in fishes, 358- 

 360; effect of mixed colors on, 310, 



316, 335, 340, 362, 363- 

 Regulation, in behavior, 50, 377; 

 Chapters 13, 14, and 20. See 

 Jennings. 



