INTELLIGENCE OE LARViE- CATERPILLARS, 
237 
Common cabbage caterpillar, which, when building web under 
stone or wooden surfaces, previously covers a space with a web 
to form a base for supporting its dependent pupa, when building 
a web beneath a muslin surface dispenses with this base 
altogether : it perceives that the woven texture of the muslin 
forms facilities for attaching the threads of the cocoon securely 
enpug'h to support the weight of the cocoon without the neces- 
sity of making the usual square inch or so of basal support . 1 
The instincts of the larva of the Tinea moth are thus 
described by Reaumur : — - 
It feeds upon the elm, using the leaves both as food and 
clothing. To do this it only eats the parenchyma of the leaf, 
preserving the upper and under epidermal membranes, between 
which it then insinuates itself as it progressively devours the 
parenchyma. It, however, carefully avoids separating these 
membranes where they unite at the extreme edge of the leaf, 
which is designed to form 6 one of the seams of its coat.’ The 
cavity when thus excavated between the two epidermal mem- 
branes is then lined with silk, made cylindrical in shape, cut off 
at the two ends and all along the side remote from the ‘ seam/ 
and then the two epidermal membranes sewn together along the 
side where they have had to be cut in order to separate them 
from the tree. The larva now has a coat exactly fitting its body, 
and open at each end. By the one opening it feeds, and by the 
other discharges its excrement, ‘ having on one side a nicely 
jointed seam — that which is commonly applied to its back — 
composed of the natural marginal junction of the membranes 
of the leaf.’ 
Reaumur cut off the edge of a newly finished coat, so 
as to expose the body of the larva at that point. The 
animal did not set about making a new coat ah initio , as 
we might expect that it would on the popular supposition 
that a train of instinctive actions is always as mechanical 
as the running down of a set of cog-wheels, and that 
wherever a novel element is introduced the machinery 
must be thrown out of gear, so that it cannot meet a new 
emergency of however simple a character, and must there- 
fore re-start the whole process over again from the be- 
ginning. In this case the larva sewed up the rent ; and 
not only so, but 6 the scissors having cut off one of the 
projections intended to enter into the construction of 
1 Hid p. 475. 
