174 STRANGE DWELLINGS, 



rope at right angles so as to bend it, while 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 cyHnder, and 

 then crawls inside to enjoy its well-earned 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 vvell-known principle of 

 exchanging space and time for power. Although the caterpillar 

 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 multi- 

 tude 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 conse- 

 quence, by taking up a considerable time in lifting the separate 

 parts. 



Again, in the silken bands which hold the rolled leaf in its 

 place, we have an excellent example of accumulated power; 

 neither of the threads being alone capable of enduring the 

 tension, but their united strength being more than sufficient 

 for the task. The threads themselves are exceedingly elastic, 

 and by their combined force aid the caterpillar in rolling the 

 leaf. 



As soon as the caterpillar has entered its new home, it begins 

 to feed, eating the green substance of the leaf, and generally 

 leaving the nervures untouched. Sometimes the caterpillar 

 lives for so short a time that a single leaf is sufficient for its 

 subsistence ; but there are some species which are obliged to 

 repeat the task more than once. 



There are other insects which also make their habitations in 

 leaves ; but, instead of rolling up the leaf and living inside the 



