IO2 The Colours of Animals. 



swollen, and the insect, when in danger, has the 

 habit of retracting its head and front segments, 

 which gives it an additional resemblance to some 

 small reptile. That small birds are, as a matter of 

 fact, afraid of these caterpillars (which, however, I 

 need not say, are in reality altogether harmless), 

 Weissmann has proved by actual experiment. He 

 put one of these caterpillars in a tray, in which he 

 was accustomed to place seed for birds. Soon a 

 little flock of sparrows and other small birds assem- 

 bled to feed as usual. One of them lit on the edge 

 of this tray, and was just going to hop in, when 

 she spied the caterpillar. Immediately she began 

 bobbing her head up and down, but was afraid to 

 go nearer. Another joined her, and then another, 

 until at last there was a little company of 10 or 

 12 birds, all looking on in astonishment, but 

 not one ventured into the tray ; while one bird, 

 which lit in it unsuspectingly, beat a hasty retreat 

 in evident alarm, as soon as she perceived the 

 caterpillar. After watching for some time, Weiss- 

 mann removed it, when the birds soon attacked 

 the seeds. Other caterpillars also are probably 

 protected by their curious resemblance to spotted 

 snakes. 



i o. Moreover, we may learn another very interest- 

 ing lesson from these caterpillars. They leave the 

 egg, as we have seen, a plain green, like so many other 

 caterpillars, and gradually acquire a succession of 

 markings, the utility of which I have just attempted 



