INDEX 



Adder, 55 ; its elliptical pupil, 28 ; 



sense of smell, loo-i 

 African River Shrew {Potamogale) , 



209 

 Albatross, their sense of smell, 103, 



199 



Albinism, and ocular defects, 28 



Alligators, 46 ; good vision on land 

 and under water, 48-9; good 

 nocturnal vision, 49 ; hearing, 72 



Amoeba, its reaction to stimuli, 

 12576 



Amphibians; variations of sense 

 perception, 17; sight: ade- 

 quacy, 24 ; the nictitating mem- 

 brane, 25 ; observations and 

 experiments, 35-46; eye socket 

 incomplete, 140; hearing: 

 importance of, in certain groups, 

 71-2; observations, 77-8; struc- 

 ture of the ear, 174, 177; 

 SMELL : scenting powers, 9 1 , 

 102-3, 200; experiments, 103; 

 TOUCH : experiment to test re- 

 sponse, 1 1 9 



Ampullae of Lorenzini, 215 



Anableps ("Four-eyed Fish"), its 

 optical mechanism, 152-3 



Angular - acceleration - receptor, 

 219-20, 222 



Antennae : organs of touch, smell 

 and taste, 17, 109, 116; of 

 ichneumon flies, 1 18 



Ants, sensitive to odours, 98 



Apes : colour vision of anthropoid 

 apes, 68 ; sense of taste, 1 1 1 ; 

 sense of touch, 114, 120-1 



Aquatic worms, touch-receptors 

 of, 211 



Archer fish. See Toxotes 



Arthropods, 160 (an^/ j^g Insects) 



Ascidians (Sea-squirts), sight of, 

 157 



Asdic, 187 



Amelia (jelly-fish), nerve network 



of, 133-4 

 Axons, 128 



Badgers, 1 3 ; and nocturnal vision, 

 29; scenting power, 106; use of 

 scent for marking out territory, 

 107; sense of touch, 120 



Balancing sense, 219-23 



Barbel (fish), 21 1 



Barbels, as tactile organs, 2 10- 11 



Barn Owl, sight of, 60, 63 



Barrington, F.J. F., 112 



Barton, Dr., 181 



Bats : eyes of, 67 ; hearing, 70, 75, 

 84, 86; use of sonar, 183, 184-6; 

 Horseshoe Bats' use of Doppler 

 effect, 186 



Bears, short-sightedness of, 65 



Bees, 71, 226 



Beetles, 16; as food of owls, 16-21 ; 

 no significance in their hum- 

 ming noise, 71 

 See also Burying beetles 



Bellairs, Dr. Angus d'A., Reptiles, 



Beluga of White Whale. See under 

 Whales 



Birds : sight : importance of, 19; 

 colour vision, 26-7, 55-6, 150-1, 

 154; observations and experi- 

 ments, 55-65; acuity, 56, 58- 

 instinctive recognition of shape, 

 56-8; song birds and high- 

 frequency sounds, 70 ; their eye- 

 lids, 139; eyelashes, 140; keep 

 pupils fully open, 142; optical 

 mechanism, 147-8, 150-1 ; in- 

 ternal structure of the eye, 148; 

 hearing: acuity and varied 

 uses, 73, 80, 81; response to 

 alarm calls, 73-4; purpose of 



231 



