Circulation of the Blood 121 



forced out. And thus it is that by the motions of the 

 muscles and extremities, the blood contained in the 

 minor vessels is forced onwards and delivered into 

 the larger trunks. But that the blood is incessantly driven 

 from the arteries into every part of the body, there gives 

 a pulse and never flows back in these channels, cannot 

 be doubted, if it be admitted that with each pulse of 

 the heart ail the arteries are simultaneously distended 

 by the blood sent into them ; and as our learned 

 author himself allows that the diastole of the arteries is 

 occasioned by the systole of the heart, and that the 

 blood once out of the heart can never get back into 

 the ventricles by reason of the opposing valves ; if I 

 say, our learned author believes that these things are 

 so, it will be as manifestly true with regard to the force 

 and impulse by which the blood contained in the 

 vessels is propelled into every part of every region of 

 the body. For wheresoever the arteries pulsate, so far 

 must the impulse and influx extend, and therefore is the 

 impulse felt in every part of each several region ; for 

 there is a pulse everywhere, to the very points of the 

 fingers and under the nails, nor is there any part of 

 the body where the shooting pain that accompanies 

 each pulse of the artery, and the effort made to effect 

 a solution of the continuity is not experienced w r hen it 

 is the seat of a phlegmon or furuncle. 



But, further, that the blood contained in the pores of 

 the living tissues returns to the heart, is manifest from 

 what we observe in the hands and feet. For we 

 frequently see the hands and feet, in young persons 

 especially, during severe weather, become so cold that 

 to the touch they feel like ice, and they are so be- 

 numbed and stiffened that they seem scarcely to retain 

 a trace of sensibility or to be capable of any motion ; 

 still are they all the while surcharged with blood, and 

 look red or livid. Yet can the extremities be warmed 

 in no way, save by circulation ; the chilled blood, which 

 has lost its spirit and heat, being driven out, and fresh. 



