124 0 /’ viewing the Current 
fuch repeated Propulsion: and though in the 
minuted Veffels there appeared no Colour^ 
jet in the larger Vein or Artery, though 
near the End of the Tail, the Blood was 
plainly red. 
We cannot properly call any YelTel an 
Artery farther than the Pulfation reaches $ 
beyond that, and returning towards the 
Heart, it mud: be accounted a Vein: for 
Veins are only Arteries elongated; but as 
they frequently divide into Branches that 
evade Difcpyery, it is, perhaps, impoffible 
to determine exadtly where the Arterief 
end, and where the Veins begin. 
They do not always, however, branch 
out fo extremely fine before their Inoscula¬ 
tion or Communication with the Veins* for 
the fame curious Obferver tells us, that on 
each. Side the little Gridles, which gave a 
Stiffnefs to the Tail of the Fifh abovemen- 
tioned, he could fee a very open Communi¬ 
cation of the Veins and Arteries; the Blood 
running towards the Extremities, through 
Arteries, and returning back again through 
Veins that were evidently a Continuation of 
thofe Arteries, and of the fame Diameter 
with them : And this he law in thirty-four 
different Places, in as many Arteries, and as 
many Veins, The Manner whereof, as by 
hint delineated, is fliewn, Tab. XL Fig. IL 
A. A * 
