52 THE SENSES OF ANIMALS 



Regarding the colour vision of lizards, there are some 

 interesting observations to be made. Dr. Angus d'A. Bellairs, 

 in his excellent little book Reptiles (Hutchinson's University 

 Library), states that experiments with food placed on 

 coloured discs show that lizards seem to prefer grey and white 

 to colours ; but that green, which he says is the commonest 

 colour in their natural environment, was selected more often 

 when four coloured discs with food on them were offered 

 simultaneously. 



I would not question this except to say that the British 

 Viviparous Lizard and the Sand and Wall Lizards are, more 

 often than not, found in places where the yellow of sand, and 

 the brown hues of soil where heather grows, and the various 

 shades of colour of walls contain very little green. This does 

 not disprove that lizards see greens well, but there is a good 

 deal of evidence that lizards can see yellow, orange and red 

 — or at least some lizards do. This brings up another interest- 

 ing point that applies to certain lizards — the Green and Wall. 

 These species have a weakness for some fruits and will feed 

 on orange, peeled greengages (yellowish in colour) and on 

 strawberries. Of course, these fruits can be detected by their 

 scents ; but if a tank containing such lizards is divided into 

 two by means of a glass plate, and in the part shut off from 

 the lizards themselves one or other of the named fruits are 

 placed, the lizards (if hungry) will at least appear to recognize 

 them by sight and will run up to the glass partition, often 

 scratching at it when they discover the invisible barrier. 



There is a further interesting point about this fruit eating : 

 there is no doubt that lizards are normally attracted by the 

 movement of insects and so on ; but as fruit is static it is 

 obvious that movement is not essential — at least for some 

 species — and food is recognized by sight and scent. 



Some mention must be made of our Slow Worm which is, 

 of course, a legless lizard. In spite of its other common name, 

 Blind Worm, this reptile has excellent sight. Its natural food 

 consists mainly of small slugs — the grey and white species, 

 not the black or brown which would appear to be un- 

 palatable. In addition. Slow Worms will eat grubs and 

 earthworms, the latter being found under logs and stones 

 where Slow Worms frequently lie up. The slightest move- 



