INTRODUCTION. 1 1 



artery is divided, it is equally manifest that blood escapes in 

 one continuous stream, and that no air either enters or issues. If 

 the pulsations of the arteries fan and refrigerate the several 

 parts of the body as the lungs do the heart, how comes it, as is 

 commonly said, that the arteries carry the vital blood into the 

 different parts, abundantly charged with vital spirits, which 

 cherish the heat of these parts, sustain them when asleep, and 

 recruit them when exhausted ? and how should it happen that, 

 if you tie the arteries, immediately the parts not only become 

 torpid, and frigid, and look pale, but at length cease even to be 

 nourished ? This, according to Galen, is because they are de- 

 prived of the heat which flowed through all parts from the 

 heart, as its source ; whence it would appear that the arteries 

 rather carry warmth to the parts than serve for any fanning 

 or refrigeration. Besides, how can the diastole [of the arteries] 

 draw spirits from the heart to warm the body and its parts, and, 

 from without, means of cooling or tempering them ? Still fur- 

 ther, although some affirm that the lungs, arteries, and heart 

 have all the same offices, they yet maintain that the heart is 

 the workshop of the spirits, and that the arteries contain and 

 transmit them ; denying, however, in opposition to the opinion 

 of Columbus, that the lungs can either make or contain spirits ; 

 and then they assert, with Galen, against Erasistratus, that it 

 is blood, not spirits, which is contained in the arteries. 



These various opinions are seen to be so incongruous and mu- 

 tually subversive, that every one of them is not unjustly brought 

 under suspicion. That it is blood and blood alone which is con- 

 tained in the arteries is made manifest by the experiment of 

 Galen, by arteriotomy, and by wounds ; for from a single artery 

 divided, as Galen himself affirms in more than one place, the 

 whole of the blood may be withdrawn in the course of half an 

 hour, or less. The experiment of Galen alluded to is this : 

 " If you include a portion of an artery between two ligatures, 

 and slit it open lengthways, you will find nothing but blood;" 

 and thus he proves that the arteries contain blood only. 

 And we too may be permitted to proceed by a like train of 

 reasoning : if we find the same blood in the arteries that we 

 find in the veins, which we have tied in the same way, as I 

 have myself repeatedly ascertained, both in the dead body and 

 in living animals, we may fairly conclude that the arteries con- 



