. 



WALKING-STICKS AND WALKING-LEAVES. 49 



to his surprise, is not long in distinguishing others, 

 which, owing to this imitative resemblance, he may have 

 seen for a long time, have even examined with care, 

 without recognizing anything out of the way, mistaking 

 the living insects for the dead branches. 



More Means of Defence. 



Putting on one side for the present this wholesale 

 Mimicry of the Phasmidae, with its protective value, we 

 find some, at least, of the insects in the possession of 

 peculiarities which perhaps one ought to consider as 

 means of defence. The prickles and spines with which 

 the Heteropteryx, Extatosoma, and other ugly monsters 

 are clothed must make them somewhat formidable 

 morsels for insect-eaters to assail ; and there are many 

 which have even a more potent means of defence in the 

 power, to a greater or less extent, of ejecting a nauseous 

 fluid. One species is named Phasma putidum, from the 

 offensive nature of the secretion discharged. A sluggish 

 creature common in some of the United States, Aniso- 

 morpha will, if seized, emit a vapour that slightly burns 

 one's skin ; and the highly acrid fluid squirted out by 

 Graeffea coccophagus when alarmed, causes great pain, and 

 sometimes blindness, when it strikes the eyes : one of the 

 South African species is said to be able to eject its fetid 



