WALKING-STICKS AND WALKING-LEAVES. 63 



The perfection of this resemblance in certain cases one 

 cannot conceive ; it is marvellous ; no insects display 

 this kind of imitation so perfectly. Those with slender 

 body, long and cylindrical, so as to resemble sticks, 

 might be mistaken for the latter with all the minutiae of 

 knots and branches, formed by the insects' legs, which 

 may be stuck out rigidly and unsym metrically. Dr. 

 Wallace, the naturalist, familiar with them in tropical 

 forests, describes them in the Moluccas " hanging on 

 shrubs that line the forest paths ; and they resemble 

 sticks so exactly in colour, in the small rugosities of the 

 bark, in the knots and small branches imitated by the 

 joints of the legs, which are either pressed close to 

 the body or stuck out at random, that it is absolutely 

 impossible by the eye alone to distinguish the real dead 

 twigs which fall down from the trees overhead from the 

 living insects." And he adds that he has " often looked 

 at them in doubt, and has been obliged to use the sense 

 of touch to determine the point." Some are small and 

 slender, like the daintiest of straws or twigs ; their body 

 sometimes an inch and a half, sometimes barely an inch 

 long, the legs like threads; others are of a much larger and 

 stouter kind. The larger wingless sticks (see Fig. 15) 

 are often eight inches to a foot long. Many of these 

 are hardly thicker than a knitting-needle. In Mexico, 

 for instance, Phanocles is about eleven inches long in all, 

 and exhibits the odd knitting-needle effect, enlarging 



