114 THE UNIVERSE. 



the magnificent spectacle offered by the movement of the 

 blood. The heart is represented by a long vessel, which 

 occupies all the back of the animal, and into which the cir- 

 culating fluid precipitates itself by eight or ten lateral open- 

 ings, like small streams converging towards a more impetu- 

 ous current. As many valves rise and fall to allow entrance 

 to the fluid and hinder its return. In the interior of this 

 lengthened heart larger valvules, to the number of six or 

 eight, are folded back against the wall to let the blood pass 

 forward, and reopen directly afterwards, during each con- 

 traction, in order to prevent its flowing backwards. Vessels 

 arranged in loops are distributed to all the members. 



The course of the blood in the colossal insect seen upon 

 the screen resembles so many little streams bearing glob- 

 ules more or less crowded together. This is proved by the 

 strictest evidence, and yet who would believe that Cuvier 

 and his school would never credit this phenomenon ? In- 

 stead of looking, which was so easy, they preferred to deny 

 the circulation in the insect, and to regard its wonderful 

 heart as a simple secreting vessel affected by contractile 

 movements. It is thus that physiological science advances ; 

 a hundred battles are requisite to make men admit the 

 most easily verified truth. 



With us, as with all the large animals, the air rushes into 

 the respiratory apparatus, without the least check, by a 

 simple and very ample opening ; all the impurities in the 

 air may be swallowed, to the defilement of our lungs. 



Insects, on the contrary, inspire the atmospheric air 

 through several orifices, and this is well purified before it 

 is introduced into the organism. For this purpose all their 



