120 WILLIAM HARVEY 



tinuing unaffected, this is an obvious indication that the 

 blood passes from the arteries into the veins, and not from 

 the veins into the arteries, and that there is either an an- 

 astomosis of the two orders of vessels, or porosities in the 

 flesh and solid parts generally that are permeable to the 

 blood. It is farther an indication that the veins have fre- 

 quent communications with one another, because they all 

 become turgid together, whilst under the medium ligature 

 applied above the elbow; and if any single small vein be 

 pricked with a lancet, they all speedily shrink, and disbur- 

 thening themselves into this they subside almost simulta- 

 neously. 



These considerations will enable anyone to understand 

 the nature of the attraction that is exerted by ligatures, and 

 perchance of fluxes generally ; how, for example, when the 

 veins are compressed by a bandage of medium tightness 

 applied above the elbow, the blood cannot escape, whilst it 

 still continues to be driven in, by the forcing power of the 

 heart, by which the parts are of necessity filled, gorged with 

 blood. And how should it be otherwise? Heat and pain 

 and a vacuum draw, indeed; but in such wise only that 

 parts are filled, not preternaturally distended or gorged, and 

 not so suddenly and violently overwhelmed with the charge 

 of blood forced in upon them, that the flesh is lacerated 

 and the vessels ruptured. Nothing of the kind as an effect 

 of heat, or pain, or the vacuum force, is either credible or 

 demonstrable. 



Besides, the ligature is competent to occasion the afflux in 

 question without either pain, or heat, or a vacuum. Were 

 pain in any way the cause, how should it happen that, with 

 the arm bound above the elbow, the hand and fingers should 

 swell below the bandage, and their veins become distended? 

 The pressure of the bandage certainly prevents the blood 

 from getting there by the veins. And then, wherefore is 

 there neither swelling nor repletion of the veins, nor any 

 sign or symptom of attraction or afflux, above the ligature? 

 But this is the obvious cause of the preternatural attraction 

 and swelling below the bandage, and in the hand and fingers, 

 that the blood is entering abundantly, and with force, but 

 cannot pass out again. 



