

152 THE INSECT WORLD. 
shortens itself, and when it consequently distends the part of 
its body which is outside the old skin, that part acts against the 
edges of the slit, and gradually pushes the old skin upwards. 
Thus the caterpillar skin ascends, its plaits are 
pushed nearer and nearer together, and it is soon 
reduced to a packet so small that it covers only 
the end of the tail of the chrysalis (Fig. 106). 
But here comes the culminating point, the 
most difficult part of the operation. The pupa, 
which is shorter than the caterpillar, is at some 
distance from the silky network to which it 
must fix itself; it is only supported by that 
i Sapte extremity of the caterpillar’s skin which had not 
the operation of east’, Deen split open. It has neither lees nor arms, 
seam Ua cis yet it must set itself free from this remaining 
part of the skin, and reach the threads to which it is to suspend 
itself. 
The supple and contractile segments of the chrysalis serve for 
the limbs which are wanting to it. Between two of these seg- 
ments, as with a pair of pincers, the insect seizes a portion of the 
folded skin, and with such a firth hold that it is able to support 
the whole of its body on it. It now curves its hinder parts 
slightly, and draws its tail entirely out of the sheath in which it 
was enclosed. It then reposes for an instant only, for it has not 
yet finished the laborious operation of its deliverance. Tt must 
free itself entirely from the dry skin which surrounds the ex- 
tremity of its body. 
The insect curves the part which is below its tail in such a 
manner that that part can embrace and seize the packet to which 
it holds on. It then gives to its body a violent shock, which 
makes it spin round many times on its tail, and that with great 
rapidity. During all these pirouettes the chrysalis acts against 
the skin ; the hooks of its legs fray the threads, and break them 
or disentangle themselves from them. Sometimes the threads do 
not break at once. Then the animal recommences its revolutions 
In an opposite direction, and this time it is almost certain to 
succeed. Réaumur, however, saw a pupa which, after having 
tired itself in vain in its endeavours to get entirely free of its 

