40i INSECTS. 



a greater change in the economy of the animal than any of the pre- 

 ceding ; for not only the skin, but the teeth, jaws, and even the 

 cranium, are left behind. The large artery which passes along the 

 body may be considered as a succession of different hearts em- 

 ployed in circulating the blood, which is at that important aera 

 observed to flow in a different direction from what it did before, 

 like the foetus of a quadruped after birth : formerly it circulated 

 from the extremity to the head ; it now pursues a course directly 

 opposite. 



The quantity of food taken by these animals in their last state is 

 comparatively small to what they antecedently devoured. For a 

 short time after their appearance on the wing, their excrements are 

 voided in a greater quantity, and are red like blood ; this is, per- 

 haps, the remains of that food which they contained before their 

 late change. The appearance of this substance on the surface of 

 the earth has at different times been regarded as portentous of 

 some heavy calamity, being supposed to be blood that had dropt 

 from the clouds. 



Some of these animals are gregarious, and live in society daring 

 every stage of their existence ; others live in that state during on 

 period of their existence only. The duration of their life is vari- 

 ous, according to the weather ; its warmth accelerates every step of 

 its progress, and its cold retards all their developments : a worm 

 produced in an early part of the summer lives only for three 

 months ; while the same species, if hatched a little later in the spa. 

 son, lives another year ; hence Reaumur has devised a method of 

 prolonging the lives of these animals greatly beyond their natural 

 course. 



The butterflies of every species are extremely prolific ; a single 

 female at one birth produces several hundred eggs : and one of the 

 most wonderful particulars in the history of these insects, is the 

 precaution with which they provide for the security of their young ; 

 some species tear off even the down from their own bodies to sup- 

 ply them with a covering. 



Various insects prey upon the butterfly, or hasten the approach 

 of its dissolution. One or two species of ichneumon perforate the 

 body of the insect while a caterpillar, and there deposit their eggs ; 

 and, although the caterpillar continues to live, and is metamor- 



