AN ANATOMICAL STUDY ON THE 



likewise conclude that arteries contain the same 

 blood as veins and nothing but the same blood.'* 



Some authors, while trying to explain this diffi- 

 culty in saying that blood is spiritous in the arteries, 

 tacitly allow that the function of the arteries is to 

 distribute the blood from the heart to the whole 

 body, and that the arteries are filled with blood. 

 Spiritous blood is none the less blood, as no-one 

 denies that the blood, even that which flows in the 

 veins, is filled with spirits. Even if the blood in the 

 arteries is very gorged with spirits, it is still believ- 

 able that these spirits are as inseparable from the 

 blood as those in the veins. The blood and spirits 

 comprise a single fluid (as whey and cream in milk, 

 or heat in hot water) with which the arteries are 

 filled, and for the distributing of which from the 

 heart the arteries exist. This is nothing else than 

 blood. 



If this blood is drawn from the heart into the 

 arteries by their diastole it follows that the arteries 

 in their distention are filled with blood, and not 

 with air, as previously discussed. If they are said 

 also to be filled from the surrounding atmosphere, 



* Harvey was philosophically interested in the ideas about the 

 origin and "perfection" of blood. Not being able to find "spirits" 

 anywhere, he is apparently trying to show that arteries as well as veins 

 contain the same fundamental fluid, blood, — and that there is no 

 "vital" difference between arterial or venous blood. See next para- 

 graph. The chemical difference between arterial and venous blood was 

 demonstrated in 1668 by John Mayow (1643-1679), but due to Stahl's 

 phlogiston theory, his ideas were neglected until they developed 

 through Lavoisier and Magnus, note 2. 



[12] 



