406 



THE LIFE OF AN INSECT. 



old, even the great Baron Cuvier himself, has 

 supposed that there was no circulation of the 

 blood in insects. But, with a magnifying glass 

 and a caterpillar before us, we shall soon be satis- 

 fied that this is a great mistake, for by carefully 

 looking along the insect's back we shall perceive 

 in that part a very evident pulsation, as though a 

 fluid were pushed at regular intervals towards the 

 head. The cut represents the 

 circulation in the vessels of the 

 larva of an Ephemera. But in- 

 sects have no heart, like that of 

 man and animals. What, then, 

 can this beating organ be which 

 we behold ? Although it is not 

 like our heart, it is nevertheless 

 an organ which serves all the 

 purpose of ours, and pumps on 

 the blood with great regularity. 

 Instead of being a muscular 

 organ of small size, but great thickness, like 

 our heart, it is in reality a long tube, called the 

 dorsal-vessel, running along the abdomen and thorax 

 of the insect, into which the blood is poured by the 

 veins, and out of which it is forced on towards the 



The circulation in an Ephe- 

 mera. The arrows repre- 

 sent, t'te direction of the 

 blood -cur rent. 



