in] of the New Physics. 59 



After speaking of the formation of blood in the liver out of 

 the chyle of the food, he goes on thus, 



"Now this blood has <>ne obvious passage only by which it 

 " can get out, namely that one which carries it into the right 

 " cavity of the heart ; and you must know that the tissue of the 

 "heart contains in its pores one of those fires without light 

 " of which I spoke above, which makes it so hot, so ardent that 

 " no sooner does the blood enter into one or other of the two 

 "chambers or cavities which are in the heart, than it imme- 

 "diately expands and dilates, just as you would find the blood 

 " or the milk of an animal would do if you were to pour it drop 

 " by drop into a vessel which was very hot. And the fire 

 " which exists in the heart of the machine which I am de- 

 ■ scribing serves no other purpose than that of expanding, heating 

 " and as it were subtilizing the blood which falls continually drop 

 " by drop, through the channel of the vena cava into the cavity 

 " of its right side, whence it is exhaled into the lung, and from 

 " the vein of the lung, which the anatomists call the vein-like 

 " artery, into the cavity of the other side, whence it is distri- 

 " buted over the whole body. 



" The tissue of the lung is so delicate and soft and always 

 • kept so fresh by the air breathed that so soon as the vapours 

 "of the blood which pass out from the right cavity of the 

 " heart enter into the artery which the anatomists call the 

 " artery-like vein, they are condensed and converted once more 

 "into blood, and then fall drop by drop into the left cavity of 

 " the heart, where if they entered without being condensed 

 " anew they would not be adequate to" nourish the fire which 

 " exists there. 



******* 



u The pulse or beating of the arteries depends on eleven 

 " little membranes which like so many little doors open and 

 " close the openings of the four vessels which open into the two. 

 " cavities of the heart. For at the moment that one of the 

 "beats ceases and another is ready to begin, the little doors 

 " attached to the openings of the two arteries are firmly closed 

 " while those at the openings of the two veins remain open, so 

 "that two drops of blood cannot help falling by these two 



