: ~ -witheut giving off any branch, or at leaft 
Sriviomen 
be boldly fated, that the whole body is an anaftomofis of vef- 
fels, a vafcular circle. ‘This faét is fo true, that although 
in fome rare cafes there may occur a conftrition and obli- 
teration of the great artery of the body, (I mean the aorta), 
immediately below the arch, which this artery makes; the 
circulation through the reft of the body, from the neck to 
feet, is not thereby {topped or obftruéted.” A 
adds this. further remarkable proof of the fa&: «I have 
a 
oO 
the arteries of the thorax, and thofe of the abdomen, 
fpace, even to the principal arterial trunks 
¢ a@t, of the free- 
dom and univerfality of the arterial anaftomofes, is highly 
important in furgery, as it enables us to tie any of the 
When an artery runs for fome length, 
any imporfant one, 
from its lize, it does not feem to be diminiflied in that fpace, 
if common modes of meafurement can be trufted. Rederer 
obferved the umbilical art 
~ thors who have confidered the fubjed, 
HEART. 
artery 
are muc 
and the parts 
WhHIC 
creafe is peculiar to’ them, in order to anfwer fome particular 
purpofe ; but the cafotid arteries, in fome animals, afford 
fufficient proof that the arteries in common become largeras 
p. I 
length, was found to fend off orty-four fmall branches, 
about the fize of the human intercoftal-arteries, with one a 
large as the ulnar. Of this: artery, a tran{verfe feCtion, of 
one inch in length, being taken from each end, and weighed ; 
7 cruple 
that from the lower end was found to weigh two f 
16 grains and a half: while that fro 
the upper end weighed 
dia In. fimilar 
grains 
referved an in 
length of the fe@tions of the trunk, I 
this be true, the arteries increafe very confiderably, not only 
imagine, if the 
«It is to be obferved, that as arteries divide, they increale 
in fize much fafter than if they did not; for initance, if a 
{ection of an artery, two inches long, is equally divided mto 
two, the fection that is the further from the heart thall be 
heavier than the other, perhaps by one grain; but if the 
moft diftant fe€tion had divided into two branches, the two 
in and a half heavier} 
if three branches, two grains heavier, &c."’ 1 a 
- ment, Phytioleg. te 
ter of the aorta is lefs confiderable than that of all its brani? i 
united. This is proved by comparing a-trunk with the ee 
branches formed from it ; the latter furpafs it aie: 
and as the proportion is conftantly the fame in all the fu whl 
fions, it muft be obvious that the capacity ofth i 
is conftantly increafing. The amoun : 
has been varioufly ftated, and: 
in the firft fe@ion ef the fecond book of his Elemen' 
himielf cive 
tween Be 
4 
they are to fupply, it may be fuppofed that this in- 
- 
