d from the extreme parts back again to the centre. Finally, upon
grounds of circulation, with the same elements as before, it will be
obvious that the quantity can neither be accounted for by the ingesta,
nor yet be held necessary to nutrition.

"Now let any one make an experiment on the arm of a man, either using
such a fillet as is employed in blood-letting or grasping the limb
tightly with his hand, the best subject for it being one who is lean,
and who has large veins, and the best time after exercise, when the body
is warm, the pulse is full, and the blood carried in large quantities
to the extremities, for all then is more conspicuous; under such
circumstances let a ligature be thrown about the extremity and drawn
as tightly as can be borne: it will first be perceived that beyond the
ligature neither in the wrist nor anywhere else do the arteries pulsate,
that at the same time immediately above the ligature the artery begins
to rise higher at each diastole, to throb more violently, and to swell
in its vicinity with a kind of tide, as if it strove to break through
and overcome the obstacle to its current; the artery here, in
short, appears as if it were permanently full. The hand under such
circumstances retains its natural color and appearances; in the course
of time it begins to fall somewhat in temperature, indeed, but nothing
is DRAWN into it.

"After the bandage has been kept on some short time in this way, let
it be slackened a little, brought to the state or term of middling
tightness which is used in bleeding, and it will be seen that the
whole hand and arm will instantly become deeply suffused and distended,
injected, gorged with blood, DRAWN, as it is said, by this middling
ligature, without pain, or heat, or any horror of a vacuum, or any other
cause yet indicated.

"As we have noted, in connection with the tight ligature, that the
artery above the bandage was distended and pulsated, not below it, so,
in the case of the moderately tight bandage, on the contrary, do we find
that the veins below, never above, the fillet swell and become dilated,
while the arteries shrink; and such is the degree of distention of the
veins here that it is only very strong pressure that will force the
blood beyond the fillet and cause any of the veins in the upper part of
the arm to rise.

"From these facts it is easy for any careful observer to learn that the
blood enters an extremity by the arteries; for when they are e