240 LIFE AND HER CHILDREN. 
wings, his six true feet, his antennae, and his sipping 
trunk, have all begun to form, but are far from com- 
plete ; and to keep them safe till they are full grown, 
a clear fluid oozes out and flows over all, hardening 
into a firm transparent case ; and as in some butterflies 
the reflection of light from the under surface of this 
case has a golden tint, the name of chrysalis (chrysos, 
gold) has been given to the still and quiet form ; 
but the word pupa (doll) is perhaps better, because 
many have not this golden hue. 
It is within this sheath that in about three weeks 
the butterfly's body is gradually formed, and all the 
fat which the caterpillar had stored in the spaces of 
its body is worked up into muscle and nerve and 
egg-producing parts. At last all is complete ; the 
head, shoulders, and abdomen have taken on their 
real shape ; the delicate tinted scales which cover the 
wings, and deck them with gorgeous colours,*" are 
full grown ; the wings themselves, made of two layers 
of skin between which are the air-tubes and the 
veins presently to be filled with colourless blood, are 
all ready ; while the little pockets in the body which 
make the full-grown insect so much lighter than 
the caterpillar, are waiting to be expanded with air. 
The nerves begin to send messages to the limbs to 
move, and the perfect butterfly, splitting its trans- 
parent covering, creeps out into the world, slowly but 
surely inflates its body and wings, and letting them 
dry in the sun, soars off to sip the flowers and find 
a mate. 
But what a different creature we have here from 
* Hence the name Lepidoptera (lepis a scale, pteron a wing), or 
scale-winged insects. 
