THE ANIMAL KINGDOM. 125 



Ephemeron only lives on love; its digestive apparatus is 

 quite annihilated. 



Some Hemiptera are, however, all through life extremely 

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

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

 organization does not alloAv of such a thing. Not having 

 any apparatus for forming a vaciuim and drawing 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 Avhich extends a gutter. In this four delicate bristles 

 move like pistons, and in the course of their action to and 

 fro attract the liquids of plants and animals so soon as 

 ever the insect has pierced the envelojoe with the point of 

 its beak. Thus when the hateful 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 admired and so 

 admirable, is nevertheless only a very coarse forcingqoump 

 compared with that of an insect. All the apparatus of 

 the central organ of circulation is limited to two large 

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

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

 aid of the solar microscope, we project all the transparent 

 body of an Ephemera upon a huge screen, one is aston- 

 ished at the magnificent spectacle off'ered by the movement 

 of the blood. The heart is represented by a long vessel 

 Avliich occupies all the back of the animal, and into which 

 the circulating fluid precipitates itself by eight or ten lateral 

 openings, like small streams converging towards a more 

 impetuous current. As many valves rise and fall, to allow 

 entrance to the fluid and hinder its return. In the in- 



