DISCOVERY OF CIRCULATION OF THE BLOOD. 297 



dilatation of the artery by the contraction of the heart, which is the 

 truth. 



Galen also taught that there are two kinds of blood, the sjnritual 

 blood of the arteries and left ventricle, and the venous blood of the 

 right side of the heart and veins, the red and the black blood. These 

 were great strides in the right direction, and yet this wonderful genius 

 was the author of some grave errors. He believed it necessary that a 

 certain portion of spirit should be mixed with the venous blood to 

 render it fit for nutrition, and this he conceived took place by the 

 transmission of arterial blood through little holes in the ventricular 

 septum which he called " foramina." He taught that the arterial 

 blood nourished organs of a light and delicate texture such as the 

 lungs, while the venous blood nourished the grosser organs, such as 

 the liver. 



The early modern anatomists believed the septum was perforated, 

 and saw with the eyes of faith the " foramina " on account of their un- 

 questioning confidence in the infallibility of Galen as an authority. 

 Mondinus, who flourished in the fourteenth century, the first anatomi- 

 cal writer after Galen, said the septum was perforated, and twenty 

 others reiterated it. 



Berrenger de Carpi, who wrote and published his anatomical work 

 in 1521, was the first to waver, and say that the openings in the sep- 

 tum loere oyily to he seen with difficulty. 



That I may pass no one who has been credited by any writer with 

 even the least knowledge of the circulation, or who has even hinted a 

 better understanding of it than those already mentioned, I come next 

 in the order of time to Nemesius, who was Bishop of Emissa, a city 

 of Phoenicia, at the latter end of the fourth century. He was not 

 properly a medical writer, though he wrote a treatise concerning the 

 " Nature of Man." The editor of the Oxford edition of this work 

 (1671) contends that Nemesius understood and described the circula- 

 tion of the blood in plain terms ; while Dr. Freind, in his " History of 

 Physic," denies that he had anything more than a vague notion of this 

 function. I copy the words of Nemesius as translated by Freind for 

 the benefit of the curious : 



" The motion of the pulse takes its rise from the heart, and chiefly from the 

 left ventricle of it ; the artery is with great vehemence dilated and contracted, 

 by a sort of constant harmony and order. "While it is dilated, it draws the 

 thinner part of the blood from the next veins, tlie exhalation or vapor of which 

 blood is made the aliment for the vital spirit. But, while it is contracted, it ex- 

 hales whatever fumes it has through the whole body, and by secret passages. 

 So that the heart throws out whatever is fuliginous, through the mouth and the 

 nose by expiration." 



Thus it appears that Nemesius had a little insight of the circula- 

 tion 1,500 years ago, yet so imperfect that he neither comprehended it 

 himself nor made it understood by any who followed him. 



