142 THE BOOK OF A NATURALIST 



lies motionless in the path, he certainly sees it, but 

 without distinguishing it as a serpent. The vari- 

 coloured surface it rests on and with which it is 

 in harmony is motionless, consequently without 

 animal life and safe to tread on a rough flooring 

 composed of mould, pebbles and sand, dead and 

 green herbage, withered leaves, twisted vines, and 

 sticks warped by the sun, brown and grey and 

 mottled. But if the smallest thing moves on that 

 still surface, if a blade trembles, or a minute insect 

 flutters or flies up, the vision is instantly attracted 

 to the spot and concentrated on a small area, 

 and as by a flash every object on it is clearly seen, 

 and its character recognised. Those who have 

 been accustomed to walk much in dry, open places, 

 in districts where snakes are abundant, have often 

 marvelled at the instantaneous manner in which 

 something that had been previously seen as a mere 

 strip or patch of dull colour on the mottled earth, 

 as a part of its indeterminate pattern, has taken 

 the serpent form. And when once it has been 

 recognised as a serpent it is seen so vividly and 

 in such sharp contrast to its surroundings as to 

 appear the most conspicuous and unmistakable 

 object in nature. Why, in such cases, they ask in 

 astonishment, did they not recognise its character 

 sooner? I believe that in such cases it is the 

 suddenly exserted, glistening, vibrating tongue that 

 first attracts the eye to the dangerous spot and 

 reveals the serpent to the mind. 



This warning character is, I believe, as has 



