240 THE LIFE OF AN INSECT. 



of which a copy is furnished at page 161. He 

 found that they are protected by little valve- 

 like contrivances, just as our mouths are protected 

 by our lips ; and these can be opened or closed at 

 pleasure by the creature ; so that if plunged into 

 water, that fluid cannot enter the insect's body, for 

 all its little doors and there are no fewer than 

 eighteen of them ! are fast shut. Singular to say, 

 however, if plunged into oil, the oil has the power 

 of entering them, and the pupae may be thus 

 drowned. 



It is very easy to put the fact of the breathing 

 of the pupa, inanimate as it appears, to a certain 

 test. By taking a wine-glass half full of water, 

 and putting it under an air-pump, and then ex- 

 hausting the air, we shall be able to extract the 

 air which exists dissolved in the water : or some 

 water that has been boiled and allowed to cool 

 will do as well. If we now put a pupa into this 

 water, and again exhaust the air from the receiver, 

 we shall notice, at the second stroke of the piston, 

 a number of little jets of air come from the insect's 

 body at the places where the spiracles are situated, 

 thus clearly proving that the creature breathes air 

 by this apparatus. The fact may be tested also 



