Note 4 — Chapter IX
Reading edition
It is not a perfectly accurate statement that the temperature of venous and arterial blood is precisely the same. The latest and best experiments concur in showing that arterial blood, at least in the heart and the great arterial trunks, is one or two degrees warmer than venous blood. The weight of evidence from experiment is also in favour of the opinion, that the different parts of the body are somewhat less warm as they recede from the lungs and heart; but the difference is so slight that it may be disregarded in the general argument.