If0 THE PHILOSOPHY 



fbrmly been attended with the fame event. A carp, iri a 

 large vefTel full of water, was placed in the receiver of an- 

 air-pump. In proportion as the air was exhaufted by work- 

 ing the pump, the furface of the animal's body was covered 

 with a number of bubbles. The carp loon breathed quicker, 

 and with more difficulty : A little after, it rofe to the fur- 

 face in queft of air. The bubbles on its furface next difap- 

 peared \ the belly, which before was greatly fwoUen, fudden- 

 ly collapfed ; and the animal funk to the bottom, and expir- 

 ed in convulfions. 



Thus the refpiration of air is as necefTary to the exiftence 

 of fifhes as to that of land-animals ; for none of them can 

 live long when deprived of this vivifying element. Fiflies, 

 indeed, feem to require a fmaller quantity of air than ani- 

 mals who have a conftant and free communication with the 

 atmofphere. The bodies and fluids of fifhes are colder than 

 thofe of land-animals ; a^d, of courfe, if Do£lor Crawford's 

 theory be well founded, iiflies require lefs air to fupport the 

 proportionally fmall quantity of heat they pofTefs. 



An analogy between fifhes and birds deferves here to be 

 noticed. Both of thefe clafTes of animals are rapid in their 

 motions ; and both of them^ befide refpiring by lungs or 

 gills, have receptacles of air within their bodies. Fifhes 

 tranfmi^ fmall quantities of air through their gills ; but Na- 

 ture has provided mofl of them with air-bags or bladders, 

 which may anfwer the double purpofe of enabling them to 

 afcend and defcend in the water, and to communicate a vital 

 principle to their \thole fyflem. 



We fhall conclude this fubje(St with an account of the 

 modes employed by Nature for tranfmitting air into the bo- 

 dies of INSECTS. 



In this feemingly contemptible, and often noxious clafs of 

 sbnimals. Nature has exhibited a wonderful diverfity of form, 

 «f manners, of inftinds, of deformity, and of beauty. But, 



