MAY 105 



of moderate power will serve to reveal a sharp beak or 

 borer projecting from the under-side of its head. "With 

 this it punctures the shoot of some plant, causing the 

 sap to exude, some of which it swallows for its own 

 nutriment, and allows the rest to gather round it as 

 a bath. While thus engaged, the lower part of the 

 creature's body — the abdomen — is kept in rapid motion 

 up and down. The tip of the abdomen is fitted with 

 a delicate apparatus which acts as a pair of bellows, 

 the up-stroke drawing in air, the down-stroke expelling 

 it into the bath of sap, the double process causing the 

 formation of an infinite multitude of exceedingly small 

 bubbles. 



But it has been proved by experiment that bubbles 

 formed in the pure sap exuding from the punctured 

 plant have no more persistence than those produced in 

 pure water. Something is wanting to cause the bubbles 

 to endure, just as a boy must add soap to water before 

 he can blow bubbles that will float for a few moments 

 in the air. The larva of the jack-jumper is equal to the 

 occasion. Within its microscopic carcase it distils a 

 glairy, albuminous fluid far more eff'ective than soap, 

 which, when exuded from its entrails, mixes with the 

 sap and gives the bubbles such consistency that they 

 will endure exposure to frost or scorching sun with- 

 out collapsing. The foam-mass therefore lasts without 

 diminution until such time — a fortnight or so — when 

 the larva shall have fed its fill, grown to full size, and 

 exchanged its yellow coat for a green one. It then 

 drops to the ground, buries itself, and becomes a pupa 

 until it is ready to emerge as a perfect jack-jumper. 



