60 MOTION OF THE 



in order to have the flow more free, did the blood descend by 

 the veins from superior to inferior parts ; but as it is elsewhere 

 forced through the extreme arteries into the extreme veins, and 

 the return in these last is opposed by the ligature, so do they 

 fill and swell, and being thus filled and distended, they are 

 made capable of projecting their charge with force, and to a 

 distance, when any one of them is suddenly punctured ; but the 

 fillet being slackened, and the returning channels thus left 

 open, the blood forthwith no longer escapes, save by drops ; and, 

 as all the world knows, if in performing phlebotomy the bandage 

 be either slackened too much or the limb be bound too tightly, 

 the blood escapes without force, because in the one case the 

 returning channels are not adequately obstructed ; in the other 

 the channels of influx, the arteries, are impeded. 



CHAPTER XII. 



THAT THERE IS A CIRCULATION OF THE BLOOD IS SHOWN FROM 

 THE SECOND POSITION DEMONSTRATED. 



IF these things be so, another point which I have already 

 referred to, viz., the continual passage of the blood through 

 the heart will also be confirmed. We have seen, that the 

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

 into the arteries ; we have seen, farther, that almost the whole of 

 the blood may be withdrawn from a puncture made in one of 

 the cutaneous veins of the arm if a bandage properly applied be 

 used ; we have seen, still farther, that the blood flows so freely 

 and rapidly that not only is the whole quantity which was con- 

 tained in the arm beyond the ligature, and before the puncture 

 was made, discharged, but the whole which is contained in the 

 body, both that of the arteries and that of the veins. 



Whence we must admit, first, that the blood is sent along with 

 an impulse, and that it is urged with force below the fillet ; for 

 it escapes with force, which force it receives from the pulse and 

 power of the heart ; for the force and motion of the blood are 

 derived from the heart alone. Second, that the afflux proceeds 

 from the heart, and through the heart by a course from the great 

 veins [into the aorta] ; for it gets into the parts below the liga- 



