212 NATURE'S STORY OF THE YEAR 



chirped slowly at first, in the manner of the hedge 

 cricket, and afterwards more quickly, for their 

 pedigree is a long one, dating back to the coal 

 period ; but in the higher region of bird-song 

 there is some evidence that a similar line of 

 progression, by mere repetition, has been fol- 

 lowed. 



Grasshoppers having lived for so long a time on 

 the earth, it is not surprising that their notes 

 should be produced by the long limbs which have 

 been the chief means whereby the creatures have 

 escaped from enemies, nor that the sounds should 

 be, in a measure, of the character of those caused 

 by the insect rapidly traversing a dense growth of 

 grass-stems. Similarly the rustling snake hisses, 

 and the squirrel, which in retreating causes a 

 violent swishing of little branches, has an alarm 

 cry which may be perfectly imitated by swishing 

 with a bare young hazel twig of a yard in length. 



Like the reptile, another descendant from the 

 hotter periods of the world, the grasshopper is 

 keenly sensitive to warmth, and loves it. Towards 

 the end of the afternoon it seeks the very warmest 

 spot in its nook for basking out the day, and often 



