70 INTRODUCTION 



monly said, that the arteries carry the vital blood into the dif- 

 ferent parts, abundantly charged with vital spirits, which cherish 

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

 them wheai exhausted? 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 deprived 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 their diastole draw spirits from the heart to warm 

 the body and its parts, and means of cooling them from with- 

 out? Still further, 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 con- 

 tain and transmit them; denying, however, in opposition to the 

 opinion of Columbus, that the lungs can either make or con- 

 tain spirits. They then assert, with Galen, against Erasistratus, 

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

 These opinions are seen to be so incongruous and mutually 

 subversive, that every one of them is justly brought under sus- 

 picion. That it is blood and blood alone which is contained in 

 the arteries is made manifest by the experiment of Galen, by 

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

 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 the blood may be withdrawn in the course of half an hour or 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 lengthwise you will find nothing but blood " ; and thus 

 he proves that the arteries contain only blood. And we too may 

 be permitted to proceed by a like train of reasoning: if we find 

 the same blood in the arteries as in the veins, after having tied 

 them 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 contain the same blood as the veins, 

 and nothing but the same blood. Some, whilst they attempt to 

 lessen the difficulty, affirm that the blood is spirituous and arteri- 

 ous, and virtually concede that the office of the arteries is to 

 carry blood from the heart into the whole of the body, and that 

 they are therefore filled with blood; for spirituous blood is not 



