192 LARGE CABBAGE BUTTERFLY. 
The caterpillars of the Cabbage Butterfly, like 
various other species, have a particular mode of 
climbing, which is either by a sort of ladder or 
single rope of their own construction. There are 
few persons who have lived in the country but 
must have noticed the larva of this insect climbing 
up a wall, or over the glass of a window. If this 
process is closely observed, on the square which the 
animal is traversing, it will be noticed, that the 
creature leaves a visible tract behind it, like a snail. 
If this is examined with a microscope, it will be 
seen that it consists of little silken threads, which 
it has spun in a zigzag direction, forming a rope- 
ladder, by which it ascends a surface it could not 
otherwise adhere to. The silk which comes from 
these spinners is a gummy fluid, which hardens in 
the air, so that they have no difficulty in making 
it stick to the glass. 
Many caterpillars that feed upon trees, particu- 
larly the Geometers, have often occasion to descend 
from branch to branch, and sometimes to the 
ground—especially previous to their assuming the 
pupa condition. Had they to descend by the trunk, 
supposing them able to traverse with ease its rugged 
bark, what a circuitous route must they take before 
they accomplish their purpose! Providence, ever 
watchful over the welfare of the most insignificant 
of its creatures, has gifted them with the means of 
attaining these ends, without all this labour and 
