116 WILLIAM HARVEY 



obvious that the blood enters a limb by the arteries, and 

 returns from it by the veins; that the arteries are the 

 vessels carrying the blood from the heart, and the veins 

 the returning channels of the blood to the heart; that in 

 the limbs and extreme parts of the body the blood passes 

 either immediately by anastomosis from the arteries into 

 the veins, or mediately by the porosities of the flesh, or 

 in both ways, as has already been said in speaking of 

 the passage of the blood through the lungs whence it ap- 

 pears manifest that in the circuit the blood moves from 

 that place to this place, and from that point to this one; 

 from the centre to the extremities, to wit; and from 

 the extreme parts back to the centre. Finally, upon 

 grounds of calculation, with the same elements as be- 

 fore, it will be obvious that the quantity can neither be 

 accounted for by the ingesta, nor yet be held necessary to 

 nutrition. 



The same thing will also appear in regard to ligatures, 

 and wherefore they are said to draw; though this is neither 

 from the heat, nor the pain, nor the vacuum they occasion, 

 nor indeed from any other cause yet thought of; it will 

 also explain the uses and advantages to be derived from 

 ligatures in medicine, the principle upon which they either 

 suppress or occasion hemorrhage ; how they induce slough- 

 ing and more extensive mortification in extremities; and 

 how they act in the castration of animals and the removal 

 of warts and fleshy tumours. But it has come to pass, 

 from no one having duly weighed and understood the 

 cause and rationale of these various effects, that though 

 almost all, upon the faith of the old writers, recommend 

 ligatures in the treatment of disease, yet very few com- 

 prehend their proper employment, or derive any real as- 

 sistance from them in effecting cures. 



Ligatures are either very tight or of medium tight- 

 ness. A ligature I designate as tight or perfect when it 

 so constricts an extremity that no vessel can be felt pul- 

 sating beyond it. Such a ligature we use in amputations 

 to control the flow of blood; and such also are employed 

 in the castration of animals and the ablation of tumours. 

 In the latter instances, all afflux of nutriment and heat 





