330 



Index 



Ultra-violet rays, reaction to, ito, 127, 

 134 f., 137, 209; effect on photo- 

 taxis, 178. 



Uniformity of reaction as evidence of 

 absence of consciousness, 29. 



Unpleasantness, 43, 55, 207, 317, 244 f., 

 249 f., 258, 260. 



Useless movements, dropping off, 219 

 ff.; persistence of, 231. 



Vanessa, 181, 184, 195. 



Vertebrates, chemical sense, 101 ff.; 

 hearing, 114 ff.; vision, 139 ff.; 

 reactions to gravity, 163 ff.; learn- 

 ing, 214, 221 ff., 232 ff., 248 f., 

 251 ff. 



Virbius, 109. 



Vision, in protozoa, 121 ff.; in ccelen- 

 terates, 123 ff.; in planarians, 126; 

 in annelids, 126 ff.; in mollusks, 130; 

 in echinoderms, 131 f.; in Crustacea, 

 132 ff.; in spiders, 135 f.; in myria- 

 pods, 136; in insects, 136 ff.; in 

 Amphioxus, 139 f.; in fish, 140 f. 

 in amphibia, 141 f.; in reptiles, 142 

 in birds, 143 f.; in mammals, 144 ff. 

 use in homing, 90, 93, 99, 139, 260 ff. 

 in rheotropism, 183 ff.; in labyrinth, 

 227 f.; binocular, 200 ff. 



Volvox, 169. 



Vorticella, 208. 



Wasps, social, 101, 257, 262, 

 solitary, 101, 139, 197, 262 ff. 



271; 



