CIRCULATION OF THE BLOOD 117 



being prevented by the ligature, we see the testes and 

 large fleshy tumours dwindle, die, and finally fall off. 



Ligatures of medium tightness I regard as those which 

 compress a limb firmly all round, but short of pain, and in 

 such a way as still suffers a certain degree of pulsation 

 to be felt in the artery beyond them. Such a ligature 

 is in use in blood-letting, an operation in which the fillet 

 applied above the elbow is not drawn so tight but that the 

 arteries at the wrist may still be felt beating under the 

 finger. 



Now let anyone make an experiment upon "the arm 

 of a man, either using such a fillet as is employed in 

 blood-letting, or grasping the limb lightly 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 larger quantity 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, at the same time that immediately above the liga- 

 ture 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 over- 

 come the obstacle to its current; the artery here, in 

 short, appears as if it were preternaturally full. The hand 

 under such circumstances retains its natural colour and 

 appearance; 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 for some short 

 time in this way, let it be slackened a little, brought to 

 that state or term of medium tightness which is used in 

 bleeding, and it will be seen that the whole hand and 

 arm will instantly become deeply coloured and distended, 

 and the veins show themselves tumid and knotted; after 

 ten or twelve pulses of the artery, the hand will be per- 

 ceived excessively distended, injected, gorged with blood, 

 dransn, as it is said, by this medium ligature, without pain, 



