CABBAGE WHITE BUTTERFLIES 163 



not very scrupulous about the position of the eggs, 

 and will sometimes lay them on the upper surface of 

 the leaf. 



The eggs, when examined by a lens, are seen to be 

 enclosed within a flask-shaped cell, on which is a 

 delicate relief pattern. The egg-shell is quite im- 

 pervious to liquids. I once wished to mount a number 

 for microscopic examination. Knowing that the 

 larvae, if not killed, would by and by emerge and 

 break the shell, I resolved to soak the eggs in strong 

 alcohol for some days. This was done, and then the 

 eggs were cemented upon a glass slip. But they 

 hatched out all the same, and all the egg-shells were 

 destroyed. Plunging the eggs into boiling water is a 

 better expedient. 



In ten days or less the caterpillars hatch out. They 

 have the outward form usual in Lepidoptera. There 

 is a dark-coloured horny head bearing the jaws (chief 



FIG. 51. Larva of Large Cabbage White, X 2. 



among them the powerful mandibles), a pair of eye- 

 spots, and a minute pair of antennae. All these 

 require magnifying power for convenient observation. 

 There are three pairs of thoracic legs, and further 

 back four pairs of prolegs, besides a pair of claspers 

 at the hinder end of the body. Except where reduced 



M 2 



