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 
6 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 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 well-known principle of i; 
exchanging space and time for power. Although the caterpillar I 1 
cannot by any exertion of strength roll up the leaf in one I 
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. I 
There are other insects which also make their habitations in 
leaves ; but, instead of rolling up the leaf and living inside the 
