oo 
ficthy fide 3 of the veiaitricles feparate from the feptum. The 
auricles pafs in ftate, *their convex furfaces 
afcending, and eis ing again Peictel: out.’ In this relaxed 
ftate of the fibres, the fides of the — offer no refiflance 
to the new bi arriving | quantity of b Sir very gently 
impelled, or the current of blood idan the veins, is fui- 
ficient to pioneaylidi the filling of the cavities. 
Afterthefe general obfervations, we proceed to detail the 
motions of the individual parts oi oaeeai A {mall portion 
auricle, is mufcular, and 
their blood by 
a itrong and manife chatiaiaions into the auricle, and are 
then dilated by the current arriving from behind. The 
is auricle is diftended ‘by the blood received from the 
vene cave, becomes turgid, and has a violet colour from 
he arknels of the contained fluid. It is contratted im- 
there ar are no valves at the mouths of the veins; it flows back 
into the cave, and the reflux, which we have already {poken: 
of in a former part of this article, extends to various lengths 
from the heart. In_a living and healthy animal, the reflux, 
is probably not sain as it is oppofed by. the rete at 
of the column containe the w — venous fyfte » and 
the oa pore] obitacle to hi tranfiniffion of the: ‘fa id 
= the lungs. 
‘The fecond and principal paffage af the blood. from the 
thr 
auricle, . is into the ventricle, ium venofum. 
The 
the time aie the 
pci auricle Sapehek aiehencnde is loofe 
- and relaxed; for if the ater were ftill in its fyttole, its 
Pia ttrength would preven ale —— diftended by 
weak atiricle.” The and a arrives therefore in the ven- 
ete, ills’ and dilates it: and" the oie of its diftenfion 
#mounts to from the auricle. 
Catia eeviedt ‘by the prefence of the blood, which 
" diftends 22 Poccavereneee contraéts ; and there’ are two att 
ich the blood may efcape; it may flow back 
into the wit: whence it has arrived, or it may be fent 
into the pulmonary artery: The tricufpidal valve prevents 
the firlt of thefe effeas. The blood, er towards the 
Sy carries the 
ting membranous valve it t direetion unti oli it’ is 
contraction o 
oe to right “ahi with the axis, — it occupies the 
‘whole area 
m venofum, Ite 
further, be ich « 
- of 63 pounds before ‘they give ‘way 
on of blood within the conical 4 ipace cireumferibed byt 
thre Soe when the ventricle i is di {ten 
e blood principally takes, tid 
e to the idea order of the fi funétions, is 
- through the eri opening of the richt' ventricle, into es 
p ulmonary ar he time that the elevation of the! 
valve clofes i eureka orifice, the large divifion of the’ 
valve, which covers the mouth of the pape é artery, fo’ 
long as its point is eeeeaded towards the ‘apex’ of the heart, 
is removed from that fi sg and leaves tee entrance inte’ 
the veffel free. ‘The blood eafily finds its np through the’ 
figmoid valves, preffing na again{ft the fide of the canal,’ 
and defiroying their cavities; they obfrud the'months of 
the veffe only i in proportion to their 'thicknefs, which is a! 
mere line, and even this impediment is avoided b by their be-’ 
ing received into the finufes of the art ery. ‘The ventricle, 
being now empty, is relaxed, and pafles into- the ftate-of 
diaito “i 
finufes, enters and fills them, feparates: thofe floating folds. 
from the fides of the artery, and urges them towards its 
axis: when the three are fully expanded, they clofe t 
opening ie ud entirely intercept the reflux of t 
blood towards the , a5 their fize correfponds to t 
The tendinons fibres increafé the ftren 
them to fuftain better 
In the dead {abject end 
prevent: the paffage of waxen ‘injection, or of air yr impelleg. 
towards the heart; and-are faid by Haller to futtain a weight 
en-the aorta is 
tied ina living animal, as remains dfiended, as thefe valves, 
shttenn the blood ‘from e 
* 08 
fervetidns may e concernin hole veins, eS ic 
e, the mitral valve, the left ventricle, and the Sgncit 
valves of the aorta, as we have already delivered concerning 
the Cortefpondmg organs on the right de. The two ae 
perfealy refemb ble each other-in their a@ions, a blood 
» between which the pailage of the . 
throtch the lungs 3 intervenes. _ of 
Haller gives the ollowing account of the facceffion 
= in the erent parts of the heart, and of the p hes 
ceale. “ 
mena i bind os wie of thefé parts th e fit 
vene cave a ulm: are cont traéted in 
point of thie, and fill rsbe auricles. 
thefé cavities mutt be diftended 
quickly i ina healthy animal by co sdnof the 
lus third period-is the fame ‘th the eee 
