The Cabbage-caterpillar 



To see the mother at her laying is no easy 

 matter: when examined too closely, the Pieris 

 decamps at once. The structure of the work, 

 however, reveals the order of the operations 

 pretty clearly. The ovipositor swings slowly 

 first in this direction, then in that, by turns; 

 and a new egg is lodged in each space be- 

 tween two adjoining eggs in the previous row. 

 The extent of the oscillation determines the 

 length of the row, which is longer or shorter 

 according to the layer's fancy. 



The hatching takes place in about a week. 

 It is almost simultaneous for the whole mass : 

 as soon as one caterpillar comes out of its egg, 

 the others come out also, as though the natal 

 impulse were communicated from one to the 

 other. In the same way, in the nest of the 

 Praying Mantis, a warning seems to be 

 spread abroad, arousing every one of the 

 population. It is a wave propagated in all 

 directions from the point first struck. 



The egg does not open by means of a dehis- 

 cence similar to that of the vegetable-pods 

 whose seeds have attained maturity; it is the 

 new-born grub itself that contrives an exit- 

 way by gnawing a hole in its enclosure. In 

 this manner, it obtains near the top of the 

 341 



