200 M E M O I R S 5/^ /Z»^ 
our lun^s that is to fay, to divide and diflolve it, and render it 
fit for circulation. Now we find no part in fifh more proper to 
produce this effect than the 'Brouchice^ that lie like fo many 
leaves upon each other under their gills; for they receive the wa- 
ter in by the mouth, and return it by the gills, or receiving it in 
by the gills, they throw it out by the mouthy hence it is agreed 
upon by all, that the water contains ibmething that produces this 
etec}, and this feems mofi: probably to be air. That there is air 
in all water cannot be doubted after the experiment of M. Ala- 
rolkj he fet a veflel of water over the fire, lb as to drive out the 
air from it j this water he put into the air-pump to extract the air 
from it, and after that, filled a phial with it, within two or 
three fingers of the top, which fpace he left only full of air, and 
itopped the phial well, and by (baking it, the water imbibed the 
air, \b as to rife up and quite fill the phial. 
But we need not wonder that fifh cannot alfo live in the open 
air; their blood is naturally lefs hot than ours, lb that the natu- 
ral heat of our blood would be a fever in them, and prove mor- 
tal ; for the nitre of the pure air is in too great a quantity, and 
too fubtile, fo that it diffelves their blood too much, and makes 
it too fluid, whereas the nitre in the water is more grols and in 
lefler proportion; whence it gives their blood only a fluidity re- 
quifite to keep it in its natural ftate. In order to prove that it is 
in the Bronchia t\\^t this divifion is performed, we need but ob- 
ferve their extraordinary rednels above any other parts of the 
body, a proof that the blood is comminuted therein; fifli are 
alfo found to die in water frozen over, which happens plainly 
from their communication with the external air being hindred by 
the ice. The heart of a filh is different from that of other ani- 
mals, in its having but one ventricle ; for the only veflels that open 
into it are the Vena Cdva, and the J^orM, being without lungs; fo 
that by the jlorta the blood comes out of the heart, which is 
branched into a thouf md capillaries over the 'Bronchi (e^ and is after 
that reunited ; which re-union is made under the bafis of the Cra- 
mum, and becaufe the blood, when once there, hc^s no need of be- 
ing forced higher upwards, they have no occafion for a fecond 
ventricle for tfiat purpole, as terreflrial animals have ; the re-union 
of thele capillaries of the Broncbii^ being made, they form two 
large trunks, of which one proceeds towards the head, and the 
other towards the lower parts. Fiili have a diaphragm, but not 
for the lame purpofe, as in other animals that breathe ; it is al- 
ways llraight and renfe, and perpendicular to the Vertebrce, 
Their llomach is membranous, fur filh iwallow down other 
fmallcr 
