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dragonflies, and all gaily coloured insects, they are either bad 

 eating or bad stingers." On the other hand, the gorgeous tints of 

 many snakes which have been assigned by some naturalists to an 

 instinct of warning, are, according to Professor Drummond, mainly 

 for protection. 



Take, for example, the puff adder, a snake from three to five feet 

 long, and disproportionately wide, being sometimes as thick as 

 the lower part of the thigh, which looks when under a glass case, 

 a most brilliant object, but when seen against the vivid colouring 

 of a tropical forest it is scarcely distinguishable from the fallen 

 leaves. He continues, " I was once just throwing myself down 

 under a tree to rest, when, stooping to clear the spot, I noticed a 

 peculiar pattern amongst the leaves. I started back in horror to 

 find a puff adder of the largest size, its thick back only visible, and 

 its fangs within a few inches of my face as I stooped. Had it not 

 been for the exceptional caution which in African travel becomes a 

 habit, I should certainly have sat down upon it, and to sit on a puff 

 adder is to sit down for the last time. Tne peculiarity of this 

 reptile is that it strikes backward, and the moment any part is 

 touched, the head doubles back with inconceivable swiftness, and 

 the poison fangs close on their victim." Thus the colouration of this 

 reptile appears to serve rather as protection for itself than as 

 warning to its victim. 



Or again, the zebra, whose black and white stripes would seem 

 to make it such a conspicuous object, is almost invisible amid the 

 dense thickness of a tropical forest, the black and white blending 

 together to form an inconspicuous grey. So inconspicuous, says 

 Prof. Drummond, that he sometimes found himself surrounded by 

 a vast herd of zebras, of whose presence he was totally unaware 

 till it was betrayed by some movement on their part owing to his 

 approach. The spotted leopard, too, conveys the same idea of in- 

 distinctness — and along the rivers it is most difficult to ascertain, 

 without close inspection, whether the objects lying along their banks 

 are fallen trees or the mud-coloured hides of crocodiles and alligators. 



But the most striking instances of mimicry, both in form and 

 colour, are displayed in various insects of the Phasmida and 

 Mantidae order. These grass- stalk insects live among the tall 

 grasses of the forest, the brown-tinged or spotted appearance of 

 which they closely imitate ; their texture and colour are like fine 

 dried hay, but the colour varies according to the season, changing 

 in autumn from a bright red to a deep claret or tawny gold. Prof. 

 Drummond's introduction to one of these insects of the Phasmidae 

 order can best be told in his own graphic words. He says, " I had 

 stopped one day among some tall dried grass to mark a reading of 

 the aneroid, when one of the men shouted ' Cherombo ! ' meaning 



