HT AARP. 
fubftances compofing the arteries cannot be diftinguithed, 
thefe veffels are remarkable for their firmnefs, in which refpeé& 
they exceed the furrounding organs. 
adly. State of this Syftem during the Time of Growth.—At the 
—— t of “ry two yreat revolutions take place in the fyftem 
red blood ; viz. a mechanical one, if we may be allowed 
to ufe that ‘ ion, in the courfe of the blood; and an- 
other of a chemical — in the compofition of this fluid. 
commencement of refpiration may be referred partly 
to the eral poco at kind of motions, produced by the 
acute fenfations confequent on the remarkable change in the 
Cees of os child, and partly to inftinét. The commence 
ment o iration attraéts towards the lungs the blood 
which milled formerly through the canalis arteriofus. Such 
is the mechanifm of the foramen ovale, that when the two 
auricles oe an equal quantity of Prrianc their contraction 
together the fides of this 
fays Bichat, “ this aperture be n at 
vibe k blocd ceafes to pafs through it; I go 
her, and affirm, that the o ning often continues 
throu hout life. Many authors relate a les of this; 
an have met with a great number. re difpofition 
of the fides of the opening is fuch that the blood cannot pafs. 
haf the two auricles contract together, the blood, which 
from without inwards, applies the overlapping 
cages score together, and cuts off, thie commuuication be- 
cavities. "The adhefion of the parts, in moft 
they are rather agglutinated than con- 
ryt ato by the preffure 
remains. 
ble of ae pores bs live when the foramen 
* — is aan: the bn as 
porters did 
ftated by i 
When 
il 
Fle 
ie 
Het 
nN 
and firm cylin- 
sientited ‘* oppofite diretions upon 
blood which eac 
diftended tha 
veflel is invarigbly obliterated. The obliseration of the umbi- : 
‘Tical vein and arteries is coeval with thefe chan 
fundtion 
in oppofition to the whole 
—— which return it again, 
are then ri 
of de 
ane two page gar 
the blood Wy clofel in cone canalis arteriofus, 
that ag is acl clofed in abeginines of its organic con- du 
. converted into an impervious 
to the moment of conception: the former predominate to. 
wards the end of life 
“ The predominance of the fyftem of red blood continucs 
marked until the end of anst 9 That this arifes from th 
funétions of nutrition and growth i is very clear ; the arteries 
in the adult contain only what is required for the former of 
thefe ; and the wad is fuperadded in the child, 
increafed calibre is neceffary in the child, and injeétions exhi- 
bit this fa&. 
‘* As the child advances, the various parts of this fyftem 
arrive at thofe proportions with refpect to cach other, which 
we neem : n 
dly. State of the Syflem after the Growth is finifbed —Abom 
a oad of ao the in bail we ~ body is coupitie; 
‘but it fill a to A ycas in bul le generati 
ow come i 
ame time the vital 
¢ is augmented, and thefe organs are the m aM ie rab 
3 difeafe. At the fame time the difeafes produced oat > 
themfelves ; thefe marks of abua- 
erial plethora thew and 
rst blood feem to admit of a fatisfaétory folution from the 
ceflation of growth. radually an re is effa- 
blifhed between all the organs, and the ar wire that 
portionate volume, which they will san erwards. 
ro 
Bubfequently to the end of owth, the arteries are inerealed 
in denfity and thicknefs, Pheir fibres become more vor | 
’ 
nifhed. 
flefhy fibres of the heart ; in ortion as the latter be- 
comes a a lling she: blood more forcibly, are 
the former ae ak to soe this force. 
—The number of arte- 
Hence, on feparating the 
ra ry few drops of Seed ane ; the 
fkin, ialiditeell in and hard, no longer e 
a bone affords hardly any blood ; the mucous 
pale ; and the mufcles lofe their cofour. 
anatomift knows that apts fucceed a 
are more advanced in age that 
and the 
f penetrate into the fmaller branches ; and thet 
fubjeéts exhibit circumfances exadtly contrary 
Ths diminifhed quantity of red blood in the old 
relative condition of his nutrition, ® 
difplay a ur and oftielty 
duagaain F fad abd the force of 
efi expe then fo be charaéterized in childhood by 
which would form a contrat to the flowed 4 
