MOTION OF THE HEART AND BLOOD 



as in the right, why say they are for the purpose of 

 impeding the escape and reflux of spirits in the left 

 ventricle but of blood in the right? The same ar- 

 rangement cannot be suited to hinder in a similar 

 way blood as well as spirits. 



3. When the openings and vessels mutually cor- 

 respond in size, as is clear in the pulmonary artery 

 and pulmonary vein,^ why should one have a par- 

 ticular function, viz., of nourishing the lungs, but 

 the other a general function? 



4. How is it possible (as Realdus Columbus 

 notes) that so much blood is needed for the nourish- 

 ment of the lungs, with the pulmonary artery lead- 

 ing to them exceeding in size both iliac veins? 



5. Again I ask, when the lungs are so near, the 

 blood vessel to them of such size, and themselves in 

 continual motion, what is the object of the beat 

 of the right ventricle? And why did Nature have 

 to add this other ventricle to the heart for the sake 

 of nourishing the lungs? 



It is said that the left ventricle draws material 

 for forming spirits, namely air and blood, from 



' These terms in the Latin are confusing. The pulmonary artery 

 was called vena arteriosa, "the vein similar to an artery." A "vein," 

 because it carried "natural spirits" to nourish the lung, but its structure 

 was recognized to be like that of the aorta, or great artery. The 

 pulmonary vein was called arteria venosa, "the artery similar to a 

 vein." An "artery" because it carried "vital spirits" (and many other 

 things, as Harvey shows, in opposite directions!), but its structure was 

 admittedly venous. It is not always easy to keep these terms straight. 

 Even Dr. Robert Willis, whose splendid translation of Harvey for the 

 Sydenham Society (1847) 's the standard English version, slipped. 



[17] 



