Page:The Harveian oration, delivered before the Royal College of Physicians, Wednesday, June 27th, 1877 (IA b22314623).pdf/13

 movement from the vena cava through the heart and lungs into the aorta. But as, during wakefulness, the movement of native heat takes place outwards, namely, to the sensorial parts; but during sleep inwards, namely, to the heart,-it appears that during wakefulness much spirit and blood are carried to the arteries, for there is a passage from them to the nerves. But in sleep the same heat returns through the veins to the heart, and not through the arteries; for the natural entrance is through the vena cava into the heart, and not through the arteries. The proof of this is to be found in the pulses, which are large, powerful, quick, and frequent in those waking up, occurring with a certain vibration; during sleep, they are small, languid, slow, and scanty. For during sleep the native heat tends less into the arteries, but rushes more violently into them as the individual wakes up. The veins behave in a different manner, for during sleep they tumefy, but shrink in the waking state, as any one may see who looks at the veins of the hand. For during sleep the natural heat passes from the arteries to the veins by inosculations which are called anastomoses, and thence to the heart; but, as the tidal movement of the blood (exundatio) to the upper parts, and its ebb (retrocessus) to the lower parts, like Euripus, is manifest in sleeping and waking, so this kind of movement is not