: 
‘} 
PHYSICAL anv LITERARY. 443 
wake *, But, from what has been faid, it ap- 
pears, thatthe fulnefs of the pulfe in fleep, is not 
owing to the quicker circulation of the blood, 
but to a lefs degree of fenfibility in the heart, 
whereby its ventricles are not excited into 
contraction, till they have been more folly 
dilated, than ufual, by the returning blood. 
It is, however, to be obferved, that the ful- 
nefs of the pulfe in fleep, may be owing, 
partly, to the fluids paffing, with greater diffi- 
culty, thro” the very fmall lateral arteries,and 
the fecretory tubes of the glands}. For we 
know that the fulnefs or foftnefs of the pulfe 
does not depend, folely, upon the quantity of 
blood thrown out by the left ventricle of the 
heart, but alfoupon the more or lefs difficult 
paffage of this fluid thro’ the extreme arteries; 
fince, in proportion as thefe are ob{tructed 
or open, agreater or lefs refiltance will be 
oppofed to the blood projected by the heart. 
Arter what has been faid of the flownefs 
of the heart’s motion in fleep, it will be eafy 
to thew why refpiration fhould be performed, 
then, at greater intervals. 
THE 
* BoERHAAVE Inftitut. med. § 597+ 
+ Exercit. de fomno et vigilia. § xl. 
