media, by others the mufculat or fibrous coat, and by more decidedly of the mu/eular nature of thefe fibres, « # 
Bichat, la membrane propre. It is a denfe and firm cover- arterus majoribus mufculof: am carnem defcripfi, nihilque ah 
‘ing, very apparent on the large arteries, and lefs fenfible on iplis abefle volui, quo mufcul; pollent.”’  Qper, Minor, tr, 
the fmaller ramifications, on which it is gradually loft. Its p. 190. 4s! 
colour is uniform throughout: the apparent reduiefs of the Tr. Hunter, who conceived that the arteries poffels a 
branches, and pliitenat of the trunks in living animals, power of contracting like mufcles, does not deferife the 
epend merely on the tran{parency of the former. allowing fibrous coat as compofed of mufeular fibres ; nor indeed does 
the blood to be difcerned through their fides, and the opacity he fpeak very clearly on the fubje&, 
of the latter. The co our of t arterial fibre is yelowith; exiftence of mufcular fibres, fr 
er of contraGion jn 
Il ’ 
he attempts 3 fhew how the 
magnitude, which run in the mufcular interilices of the mufcular part may be diftinguifhed bytheeye. B looking 
‘body ; but an attentive examination ef thefé veffels*has ena- on the cut edge of an artery, he fays, we fhall obferve, that 
i fi an it is redder towards the Inner furface; that this darker 
re fo frequent in coloured portion begins almoft infenfibly in the larger arteries, 
‘his i and increafes in amount as the veflels become fmaller, H 
matter of doubt. Such effufions take place only from the flates further, that the difference i 
capillaries; the trunks are 
have fought in vain td difcover the tort veflels by inje@tions.”? cular fibres are intermixed. Th account on the whole is by 
‘The organization and arrangement of this covering feem no means clear; and the affertion of a differ nce between 
be uniform in all other parts of the bod 3 perhaps it outer and inner portions of ‘the fibrous coat is not 
eing intermixed, as he confiders the mufcular and elaitic 
ugnant to our obfervations on all other parts of 
achi ; 
hine. 
difpofed in fucceffive entric flrata, fo that, after When a branch arifes from any trunk, the circular fibres: 
moving the cell » the various layer of the latter are feparated, and form on each fide a half . 
without trouble, whic cumitance has led feveral circle, from the union of which an entire. circle is formed, 
authors to reprefen 8 arteries as being formed of furrounding and racing the {mall rings formed by the 
feveral coa fibres are circular, or ne ly fo ; he circular fibres of the branch. The latter are continued to 
exterior have fome attachment to the clofe cellular the Internal Prominence of the lining membrane, 
tiffue which is contiguous to them. Hence, when we remove feen on the infide of the arterial Cavity, as we have a 
the latter, a: greater or lefs number of the fibres remains deferibed, hefe projections are in fa&t made by the 
connected to it. | internal membrane may be eafily fibrous coat covered on its inner furface by the internal 
i 
feparated, without carrying away any of the arterial fibres. membrane. There is, howe 
‘Haller’s defcription of this part reprefents it as more \ 
decidedly of a mufcular nature. « Poft } recipuam are chiefly connected together by the continuity of the 
arteriz equuntur interiores carnee fibre, qu s in lular and the internal 
arterix aorte principio inprimis contemplatus fum, qua in arife from a trunk 
fede utique et copia et rubore facilius fe produnt, M 
el of the femi-circular projection, fepa- 
rating the two arteries internally. . See 
here are no longitidinal fibres, nor pares any but the 
* u m. Po 
natomieis recepta, quam primam arteriz am vo- cular ; yet a ver curfory examination will fuffice to convince 
cavit hrous. ‘In minoribus arteriis fenfim malignius us of their differences, S not red 
uibita, qua rerum | pecies ‘augetur. “- cerebri enim yatis © bo 
we aor ingame tits wrote Go oI 
- redarguit Cl. lawiglus, ut tamen pauciores faciat ”? Elem.. and eafily ftretched ; while the arterial fibres are firm a 
Phyfiol. lib, 2, feet. 1 §7. On another occafion he {peaks _folid, and break rather than give way to the ee z The : 
