E 
c6 ^" OF THE HEART, VESSELS 130.5 
7 
LEA 
bled the refe mirabile of the carotid attery. of the herbivorous. 
: » : 
quadruped, | But a nearer view will undeceivé us. ^ For'T have. — 
found, that, by elegant fnbdivifions and. folds of the meme 
; brane of the gills, their furface, in a large fkate, is nearly. 
equal to the whole external furface of the human body, . 
7. Thus in each fide of the body ofa fkate there are fout. 
double gi/I; , or gills with two fides cach, and one Éingle gill; 
or there are in all. eighteen fides or farfaces, on wehich the 
branchial artery is fpread out, ^ On each of thefe fides there are. 
about go divifions, or doublings of the membrane of the 
gils (^). Each divifion has on, each fide of it 160 fubdivi- 
fions, doublings, or folds of its membrane; the length of : 
each of which in a. very large fkate is about one- eighth of ar 
inch, and its breadth about one-fixteenth of an inch (f£). So 
that in the whole gills there are 144,000 fubdivifions, or folds, 
the two fides of each of which are equal to the 64th part of a 
fquare inch, or the furface of the whole gills in a large fkate 
is equal to 2250 fquare inches, that is, to more than 15 fqua- - 
re feet, which have been fuppofed equal to the whole ex- 
ternal furface of the human body." When after a good inject-. 
jom of the artery, a microfcope is applied, the whole extent 
9f the membrane of the gills is feen covered with a beautiful 
aet-work of exceedingly minute veffels, T 
S. As fishes taint the water they refpire, in nearly the 
fame manner as we taint the air we breathe, it appears tbat 
fome matter, either ufelefs or hurtfal, or both, is carried off 
from their blood as it paffes through their gills, "iia 
9. When diililled oil of turpentine, colonred with 
vermilion, is injected with. moderate force iuto the branch- - 
ial artery of a living or recently dead fkate, fome of the co- 
lourlefs part of the oil exfudes upon the furface of the gills, 
: But 
————— 


(e) See Tab. IF. fig. 12; 
Cf) Tab. L fig. 5. 
