LEPIDOPTERA. 149 
which elongates it; thus the split soon extends from the end or 
the commencement of the first ring as far as the other side of the 
end of the fourth. The upper portion of the body which corre- 
sponds to these four rings is then laid bare, and the caterpillar 
has an opening sufficiently large to serve it as an egress through 
which it can entirely leave its old skin. It curves its fore part, 
and draws it backwards; by this movement it disengages its head 
from under its old envelope, and brings it up to the beginning of 
the slit; at once it raises it, and puts it out through this slit. 
The moment afterwards it stretches out its fore part and lowers its 
head. ‘There now remains for the caterpillar nothing but to draw 
its hinder part from the old case.” 
This excessively laborious operation is finished in less than a 
minute. The new livery which the caterpillar has just put on is 
fresh and bright in colour. But the animal is exhausted by 
its fast, and the efforts which it has made. It requires a few 
hours in which to regain its equilibrium, and at the same time 
its former activity and voracity. 
THE CHRYSALIS, OR PUPA. 
Having attained its full development, the caterpillar ceases to 
eat, as at the approach of a moult, it empties its intestinal canal 
by copious ejections; it loses its colours, and becomes dull 
and livid, and thus prepares itself to enter a new phase of its 
existence. 
Some, when about to transform themselves into chrysalides, 
suspend themselves to foreign bodies. Others spin a cocoon, 
composed of silk and other substances, which secures them 
against the attacks of their enemies and the action of the atmos- 
phere. Those which suspend themselves can be divided under 
two heads, according to the mode of their suspension :—1. Those 
which suspend themselves perpendicularly by the tail. 2. Those 
which, after having fixed themselves by the same part, suspend 
themselves horizontally, by means of a silk thread passed round 
the body. 
To understand the difficulty which the first of these operations 
