THE ANIMAL KINGDOM. 113 



abstinent, and only feed on the juices of plants. They do 

 not suck them, although generally said to do so ; their 

 organization does not allow of such a thing. Not having 

 any apparatus for forming a vacuum and sucking up fluids, 

 they draw them off by means of the mouth, which for this 

 purpose is transformed into the most delicate little suction 

 pump that can be imagined. The lower lip represents a 

 tube terminated in a point, on the upper part of which ex- 

 tends a groove. In this four delicate bristles move like pis- 

 tons, and in the course of their action to and fro attract the 

 liquids of plants and animals so soon as ever the insect has 



56. Common Ephemera: Ephemera communis. 



pierced the envelope with the point of its beak. Thus, 

 when the bloodthirsty gnat settles on our skin and gorges 

 itself with our blood, it does not suck the fluid ; it pumps it 

 up with pistons of exquisite delicacy. 



Our heart, the structure of which is so much admired and 

 so admirable, is nevertheless only a very coarse forcing- 

 pump compared with that of an insect. All the apparatus 

 of the central oro-an of circulation is limited to two large 

 openings, each furnished with two valves or valvelets, in- 

 tended to prevent the reflux of the blood ; but if, by the aid 

 of the solar microscope, the transparent body of an Ephem- 

 era is projected upon a huge screen, one is astonished at 



