36 INTERNAL ANATOMY OF INSECTS. 



usual tests in both instances detected the conversion of 

 the oxygen present into carbonic acid a . Precisely the 

 same result was obtained by Sorg and Ellis, who, having 

 placed a number of flies in nine cubic inches of atmo- 

 spheric air, found them all dead by the third day, the 

 oxygen intirely vanished^and a quantity of carbonic acid 

 nearly equal in bulk produced b . 



It is ascertained too, that insects like other animals 

 require in the process of respiration not merely oxygen, 

 but such a mixture of it with nitrogen or azote as com- 

 poses atmospheric air: for Vauquelin found that a grass- 

 hopper placed in six cubic inches of oxygen lived only 

 half as long (eighteen hours) as another placed in eight 

 inches of atmospheric air ; its breathing was much more 

 laborious, and it died when not more than one-twentieth 

 of the oxygen had been converted into carbonic acid c . 

 That a large quantity of oxygen penetrates all parts of 

 insects, is evident also from the acid prevalent in the 

 fluids of most of them, as likewise from the wonderful 

 power of their muscles. That azote is also received, 

 seems probable from the ammonia which has been ex- 

 tracted from the fluids of many, and from the rapid pu- 

 trescence of these animals d . 



The mode, however, in which the respiration of insects 

 is carried on, differs greatly from that which obtains in 

 the higher animals. They have no lungs, no organs 

 confined to a particular part of the body, by means of 

 which the whole of the blood is regularly exposed to the 



a Ann. de Chimie, xii. 273. 



b F. L. A. Sorg, Respirat. Insect, et Verm. Ellis, Inquiry into 

 Chang, prod, on Atmosph. Air by Respirat. &c. 69. 



Ann. de Chimie, xii. 273. d Sprengel, Commentar. &c. 27 . 



