THE LILAC MOTH. 297 



That so minute a creature should roJl up the leaf by main 

 strength is of course an impossibility, and the method by which 

 that consummation is attained is so remarkable an instance 

 of practical mechanics that I must describe the operation at 

 length. 



If the reader will procure one of the rolled leaves, he will see 

 that the cylindrical portion is retained in its place by a row 

 of silken threads, which are individually weak, but collectively 

 strong, holding the elastic leaf as firmly as Gulliver was held by 

 the multitudinous cords with which he was fastened to the 

 ground. That they should hold the cylinder in shape is to be 

 expected, but the manner in which the cylinder is made is not 

 so clear. The foUowiug is the process : — 



First, the caterpillar attaches a number of threads to the 

 point and upper edges of the leaf, and fastens the other ends 

 to the middle of the leaf itself It now proceeds to perform an 

 operation which is precisely similar to the nautical method of 

 " bowsing " up a rope. In order to " bowse " a rope taut, two 

 men are employed, one of them pulling the nearly tightened rope 

 at right angles so as to bend it, whUe the other continually 

 belays it to the cleats. Now, the caterpillar performs precisely 

 this operation, but without requiring the aid of an assistant, the 

 " bowsing " being performed by its feet, and the belaying by its 

 spinneret. By thus hauling at, and tightening each line in suc- 

 cession, the caterpillar bends the leaf over slightly, and then 

 attaches a fresh series of threads to keep it in its place. By 

 repeating this process, and by continually adding fresh lines, the 

 creature fairly bends the leaf into a hollow cylinder, and then 

 crawls inside to enjoy its weU-eamed home. 



I may here point out that the whole process of rolling the 

 leaf affords an admirable example of mechanics as exhibited in 

 nature, and that it is achieved by the well-known principle of 

 exchanging space and time for power. Although the caterpUlar 

 cannot by any exertion of strength roll up the leaf in one minute, 

 it is enabled to do so by dividing the work into a multitude of 

 parts, and taking much longer time about it, just as a man who 

 cannot lift a single weight of a thousand pounds may do so with 

 ease by dividing it into ten parts, and in consequence, by taking 

 up a considerable time in lifting the separate parts. 



Again, in the silken bands which hold the rolled and elastic 



