HiE\ AL RET. 
guifhed from thefe° membranes by the kind of brittlenefs 
which it poffefles:: itis torn by very flight force 
Although this membrane is continuous over the whole 
internal furtace ace of the circulating fyitem of red blood, it 
prefents a differences of ftruéture in the different re- 
gions. s thinner in the left eine than in the cor- 
rfponding auticle, and in the arteries. is ees in 
tricle, and in the a Stach veins, of much more 
: conden dilatation than in ries, 8 Sg it and the 
fibrous coat would inevitably be burft by any con- 
fiderable dilatation. On the inner furface of the auricle and 
i culiar whitenefs, in con- 
farface of this membrane offers no obftacle to the tran‘mif- 
fion of the pret through the tubes which it lines; and the 
moifture of the part after death aris —, from fome 
adhering portion of feum, .and n m any mucous fluid, 
different from the blood, focressl by ‘the velfels of the part. 
- Folds of this membrane for 
to the fibrous coat, there is no cellular fubftance interv. ening 
between them: yet neither boiling, maceration, nor putre- 
ae produces its detachment without the affiftance of dif- 
Although the appearances of the two be very diictent, +4 
petted is very 
fliers an be we 
anic aad of the body: they 
i marked by exclufive and diftings charaGters. 
al membrane when 
Mg: se ing. ‘the co tion, are fa 
« Among all the oan fytlems,” fays nay “ this 
ee, eee sare is ie Sar a for its fingular tendenc 
offified in the 
i year-of their | 
‘ The incruftations conftant on the external 
fusface of the inner coat, fo that a thin pellicle feparates - 
‘them from the bl They do not obferve the Jaws 
common See, as eye do not exift previoufly in the 
§ 
| 
= 
e earthy aiacker 
in feparate plates of greater or lefs 
es the whole artery pee a continuous folid tube. 
branous portions connet together the feparate oes iid 
allow the veffel to accommo hie itfelf to the motions necef- 
. © long as the plates ao thin, 
remains fmoo > asin the natural 
is always depofited 
gee 
“perities.  'Phefe circumftances may be obfenied particularly 
“in the origin and courfe of the aorta. All parts of the ar- 
eem to 
erin 
3 «: Similar bony depofitions are feen int 
‘it forms the aortic and mitral vaiveeg 
oa iu the other parts of its expaniion over the i interior. of 
- 
‘terial fyitem are fubject to this kind of offification the iendE 
branches be ‘affected as frequent! 
yin left cavities of the heart. Offification of the titin 
aorta is found by morbid refearches to derange the cir- 
eihvels but that of the {maller arterial trunks and branches 
does Hot impair this funétion in the flighteft degree 
** ‘The bony depofitions, which we have jut deleribed dif. 
r from thofe, which’ come on in other parts of ‘the: body, 
tnafeinth as they are natural phenomena, while ‘the others 
fluenced by age, | 
as well as in old oe 
rial membrane may alfo occur before old age, but they 
are the mott frequent, beyond all comparifon, at that 
‘time,’ 
Of th e common Parts belonging 6 te Organifation of the cir- 
-eulating Syftem of red Blood — embranes, which comt- 
ofe the arterial tubes, are fapplied with blood by fmall 
‘arterial ramifications, called vafa arteriarum, and which 
ferve the fame purpofes here, as in other ftruétures of the 
‘body. They come from the ramifications of the furround- 
‘ing at and not from the trunk itfelf: for, if a portion of 
the common carotid be filled d with fine inje¢tion, the arte- 
ries of its coats are not in jected.’ pa a 
and fend branches. 
are dif 
ternal linings. mr I hav ve never feen,’’ he Bichat, “ any 
arteries penetrating to this coat, either after injection, 
in the livin ng — reds ook, an artery, 1 in which the 
-courfe of the blo b 
the application ne two ligatures. “In order to difti 
the arterial veffels clearly without injection, we fhould 
a trunk, as the aorta, in a young an imal whi 
died of afphyxia: all ~ {mall arteries are nae com} ‘etely 
filled with black blood. In the foetus, particularly if it 
“died from afphyxia in the’ sides an abundance of blood- 
veflels will be feen in the large arteries, whic are rendered 
me ace 
d. 
almoft livid from this cir reumftance. Ke There 
opps held in ie sont 
7 / tiffure does not feem to be coneaal into the 
Sotertices of the fibrous coat of the artery, and this =o 
ternal-coats. “I conceive,” fays Bi 
‘contributes much to the peculiar brittlene ves 
‘terizes the arterial tiffue, and which geese it to giv . 
under the application of a ligature. And onthe fame pr? 
a ee yior noua es ne 
