South American Giant Toad, 41, 



43. 

 Spaniels: their sight, 28; scenting 



powers, 105 



Spiders : sight : and courtship 

 dances, 16; number of eyes, 23, 

 161 ; observations and experi- 

 ments, 34-5 ; HEARING : experi- 

 ments on, 76 ; SMELL : special- 

 ized sense organs for, 201 ; 

 touch: keen response to, 118; 

 web-spiders' reliance on, 16 



Spiracle, 174 



Spotted Salamander, 46 



Squids, eyes of, 157, 158 



Squirrels: scenting power, 106, 

 107; hibernation, 228 



Starfish, responsive to touch, 119 



Starlings, mimicry of, 82, 83 



Statocysts, 222 



Stereoscopic sight, 146 



Stoats : sight, 66 ; sense of taste, 1 1 2 



Stridulation, 71, 76 



Swiftlets, their use of sonar, 192 



Synapse, 128 



Taeliafelina (sea-anemone), 128 



Taste, sense of: closely linked with 

 sense of smell, 16, 90, 109, 113, 

 195, 203 ; a chemical sense, 109 ; 

 taste-bulbs, 109, 203-4; of 

 aquatic animals, no; fish and 

 amphibians, iio; birds, iio; 

 taste smell relationship, iio, 

 III; mammals, in; behaviour 

 of carnivores with pregnant 

 female prey, 1 1 i-i 2 ; carnivores' 

 avoidance of gall-bladder, 112; 

 discrimination by rats, stoats, 

 monkeys, 1 12-13; response to, 

 human and animal, 204-5 ; 

 lack of distinction between 

 taste and smell in aquatic 

 animals (chemo-reception), 



205-7 



Taste-bulbs, 109; structure of, 

 203-4 



Tawny or Brown Owl : its sight, 

 60 ; field observations, 62-3 



Temperature-receptors, 2 1 3 



Tench, 191 



Terrapins, 46; response to move- 

 ment of prey in water, 48; 



INDEX 239 



hearing, 72; sense of taste, no; 

 experiment to test response to 

 touch, 119 



Terriers, scenting powers of, 105 



Third eyelid. See Nictitating mem- 

 brane 



Thirst, proprioceptive reaction to, 

 224 



Thorpe, Dr. VV. H., 83 



Thrushes, hearing of, 73 



Tits, 73 



Toads : sight : field observations 

 and experiments, 43-6; a pecu- 

 liar use of, 140; hearing: 

 importance of sound, 71-2; 

 function served by croaking, 72, 

 77; field observations on, 77; 

 smell: scenting power, 91, 102- 

 103, 200; taste: in water, no; 

 touch: sensitivity to, 119; 

 monitors: homing ability, 226 



Tongue : of snakes and lizards as 

 detector of smells, 17, 91, 200; 

 of parrots, tactile use of, 114-15 ; 

 of snakes and lizards, as means 

 of testing environment by touch, 

 200 

 See also Taste-bulbs 



Torpedo, 193, 194 



Tortoises, 46; good sight of, 24; 

 limited colour vision, 47-8; 

 hearing, 72; smell, 100; taste, 

 1 10; touch, 1 19 



Touch, sense of: and feeling, 114; 

 in different orders of animals, 

 114-16; affinity with hearing, 

 117; field observations and experi- 

 ments : vorticella, 117; hydra, 

 118; ichneumon flies, 118; 

 amphibians and reptiles, 119; 

 birds, 119; mammals, 119-22; 

 — response of sea-anemones, 1 29, 

 simplest of the senses, 1 34 ; 

 served by corpuscles and nerve- 

 endings at roots of hairs, 208-9 ; 

 whiskers as tactile organs, 209- 

 210; barbels as tactile organs, 

 2 lo-i I ; in certain invertebrates, 

 crustaceans, insects, 211-12; 

 powers of discrimination, 212- 

 213; receptors for heat, cold, 

 pain, 213-14; the generalized 

 chemical sense, 215; sensory 



