MIMICRY. 553 



it disappeared, then, rising cautiously, it exposes the tip of its 

 nose above the surface, at the same time giving it a rotary motion 

 like that of a water-bug at play. The unwary bird on the wing, 

 seeing the object near by, alights to catch it, while the Sea-lion 

 at the same moment settles beneath the waves, and at one bound, 

 with extended jaws, seizes its screaming prey, and instantly 

 devours it. * Waterton has given a very similar suggestion. 

 Beneath some agitated birds, and in the long grass, he saw 

 what was apparently "a pale green Grasshopper," fluttering 

 as though entangled in it. " Nothing more remained to be 

 done but to wait in patience till it had settled, in order that 

 you might run no risk of breaking its legs in attempting to lay 

 hold of it while it was fluttering — it still kept fluttering, and, 

 having quietly approached it, intending to make sure of it — 

 behold, the head of a large Rattlesnake appeared in the grass 

 close by. . . . What had been taken for a Grasshopper was, in 

 fact, the elevated rattle of the snake."! Aflalo has remarked: — 

 " The snake's power of fascinating birds is another moot point, 

 on which Dr. Stradlinghas offered about the best suggestion, fully 

 endorsed in Miss Hopley's charming book. His opinion is that 

 the birds mistake the quivering tongue for a worm or insect, and 

 that organ, considered by the ignorant to be endowed with ' stinging 

 powers,' may consequently act as a bait to lure the incautious food 

 within reach of the fatal jaws."! The Tree-Frog (Hyla) is of a 

 light green colour when seated upon a light green leaf, but becomes 

 dark brown when transferred to dark surroundings. " Hence 

 this animal adapts itself to the colour of its environment, and 

 thus gains protection from its enemies. "§ 



* Cf. J. A. Allen, ' Hist. N. Amer. Pinnipeds,' pp. 301-2. 



t ' Wanderings,' Wood's edit., pp. 166-7. 



J ' Sketch of the Nat. Hist. Australia,' p. 161. 



§ Weismann, 'Lectures on Heredity,' &c, Eng. transl., 2nd edit. vol. i. 



p. 309. — Weismann adds: — "That the chrornatophores do not themselves 



react upon the direct stimulus of light was proved by Lister (' Phil. Trans.' 



vol. cxlviii. 1858, pp. 627-644), who showed that blind Frogs do not possess 



the power of altering their colour in correspondence with that of their 



environment." 



(To be continued.) 



