4o6 



INDEX 



Reighard, color vision in fishes, 359, 

 360. 



Reinke, chlorophyll-absorption band, 

 312. 



Reptiles, 343- 



Rhizopods, 74; 79; 229; 233; aggre- 

 gation of, 242; 258. 



Romanes, 10; 24; 211; 235; 251. 



Roots. See Plants. 



Root-tip, function of, in reactions, 

 19, 20. 



Rothert, 12; 21; 72. 



Ryder, 247. 



Sabella microphthalmia, 247. 



Sachs, J. von, ray-direction theory 

 of orientation in plants (heho- 

 tropism, geotropism), 13-16; ag- 

 gregation of organisms due to 

 currents, 15; criticism of Darwin's 

 idea of function of root-tip in 

 movement of roots, 21; 24; 25-30; 

 3,y, 34; 38; 39; 40; 42; definition 

 of tropism, 53, 54; 57; 60; 70; 80; 

 86; ray-direction theory criticized, 

 87; 112; ray-direction theory ap- 

 plied to Vol vox, 137, 144; 149) 

 233; 314; effect of different colors 

 on reactions of seedlings, 317; 319; 

 See Ray Direction ajid Criticism. 



Sagartia, 48. 



Sand fleas, adaptation, 237, 238, 



Sarsia, 251. 



Scapholeberis armata, 214; 271; 277; 

 280; 300. 



Schafer, cause of invisibility of infra- 

 red and ultra-violet, 362. 



Schreckbewegung, origin and mean- 

 , ing of term, 17; in Euglena, 82; 

 no; 161; 233; 240; 246; 257; 259; 

 in bacteria, 325. 



Scystosiphonlomentarium, 274. 



Sea anemone, 258; 299. 



Sea squirt, 250. 



Sea urchin. See Echinoderms. 



Seedlings, orientation in light, 59- 

 73 ; change in sense of orientation, 

 265; reactions in spectrum, 314, 

 See Plants. 



Semotilus atromaculatus, 358. 



Sensation. See Psychic phenomena. 



Sensibilite differentielle, compared 

 with motor reflex, 17; 243. 



Sensitiveness, with different surfaces 

 exposed: in Euglena, 104-106, in 

 Stentor, 114, 115, 119; variation 

 in, 288-297, 301; in plants, 288, 



3^3, 319- 

 Serpula, 247; 254; 258. 



Serpula uncinata, 247. 



Setaria italica, 21. 



Shadows, reactions to, 247-250. 



Sharroc, 7. 



Shock-movement. See Schreckbewe- 

 gung. 



Shrimps, 249; 257; 260. 



Sigesbeckia, 286. 



Sign, reaction to, 243; 250; 259-263; 

 286; 292-295; 298. 



Simocephalus sima, 265; reactions 

 in spectrum, 337, 341-343, 362. 



Sinapis alba, reactions in spectrum, 

 316, 317. 



Smith, orientation in earthworms, 

 198; 201. 



Spaulding, modification in reactions 

 of hermit crabs, 296. 



Spectrum, energy distribution in, 

 304, 305; brightness distribution 

 in, 305-308; actinic effect, dis- 

 tribution in, 308-312, 360; reac- 

 tions: of plants in, 313-320, of 

 unicellular forms in, 321-332, of 

 Amoeba in, 327-332; distribution 

 of stimulating efficiency in: plants, 

 314-320; swarm-spores, 321, 322; 

 diatoms and Oscillaria, 323, 326, 

 327, ciliates, 323, flagellates, 324, 



