( 419 ) 
V% A General Idea of the SiruBure of thelnte^^ 
nal Parts of Fijh, Communicated hy Dr. Charles 
Prefton. 
F'ISH are not only different from other Animals* 
but likevvift differ very much from one another' 
there being fcarce a Species of them , that has not 
remarkable Differences : Not intending to enter 
into the feveral particularities, it fea'l iuffice 
to obferve the principal Matters wherein they differ 
from other Animals, of which the moft confiderable is 
their want of Lungs, and in their not Breathing,* 
whereas all other Animals have Lungs both Terre- 
ftrial> Volatil, and Amphibious : And in Infeds, the 
ftveral Trachea that are fpread throughout their whole 
Body ferve them inftcad of Lungs, k isneverthe- 
kfs necefiary that foniething fliould liipply this in fiflies> 
which may hav© the fame effecSt upon their Blood, as 
the Air has upon ours, by entring into our Lungs ; 
that is to fay, to divide and diffolve it, and render it fit 
fer Circulation otherwife it were in danger of Coa^ 
gulating, would become movelefs and ftagnate. Now 
we find no part in Fi(h more proper to produce this 
effed than the Bronchise that lye like fo many Leaves 
upon each other under their Gills ; for they receive the 
Water in by the Mouth, and return it by the Gills, or 
receiving it in by the they throw it out by the 
Mouth. 
It may be asked , What this is that diffolves the 
Blood in the Bronchi ie ? 
k is agreed upon by all, that the Water muil necef- 
farily contain this Body that produces the Etfed: but 
they differ in afferting what it is. It cannot be Water 
alone, 
