OF THE LARVA STATE. 63 
Caterpillars have sixteen legs, and devour their 
food by means of two jaws; they have twelve eyes, 
so exceedingly minute, as to be nearly impercept- 
ible without the aid of a microscope. 
The quantity of food which is daily eaten by a 
caterpillar is surprising, being greatly more in pro- 
portion to its bulk than is consumed by any other 
animal. Many larve eat twice their own weight of 
leaves within twenty-four hours. John Hunter as- 
signed as a cause, that their stomachs have not the 
power of dissolving vegetable matters, but merely 
the faculty of extracting a juice from them.* This 
seems indisputable from the faeces, consisting of coiled 
up hardened particles of leaves, which, after being 
immersed in water, will expand like tea leaves. The 
quantity, also, in proportion to the mass consumed, 
is farther confirmation of the fact. Colonel Marshall 
made some detailed experiments, and found that 
the larva of the Bombyx Caja, which weighed thirty- 
six grains, voided every twelve hours from fifteen 
to eighteen grains weight of excrement; while it only 
increased in weight during that time from one to two 
grains. While in this condition they generally eat 
voraciously, and repose but for short intervals. As 
they enlarge, which they do very rapidly, they cast 
their skins several times. When the larva has at- 
tained its full size, it soon afterwards ceases to eat, 
becomes excessively restless, and searches for a place, 
* Observations on the Animal Economy, p. 221. 
