152 GRAMMAR OF ENTOMOLOGY. 



CHAPTER X. 



OF THE ORGANS OF RESPIRATION. 



574. IN vertebrated animals, the lungs are 

 situated in the anterior part of the trunk : the 

 whole of the air that is appropriated to the uses 

 of the body must be inspired by the trachea, 

 which ascends from the lungs to the mouth and 

 nostrils : the trachea and lungs are the organs of 

 respiration. 



575. We find that in insects there is no part 

 appropriated solely to the organs of respiration, 

 but that they permeate every part of the body, 

 mixing with the blood-vessels, and, as we might 

 say, seeking the blood, in order to aerate it, in- 

 stead of the blood seeking the organs of respira- 

 tion by rushing into the lungs, as it does in 

 vertebrated animals. 



576. The organs of respiration in insects con- 

 sist of simple tubes, which communicate exter- 

 nally with the air, and internally with the blood : 

 the utility to all animals of imbibing air appears 



