Introduction 17 



or meaning of the pulse of the right ventricle ? and 

 why was nature reduced to the necessity of adding 

 another ventricle for the sole purpose of nourishing 

 the lungs ? 



When it is said that the left ventricle obtains materials 

 for the formation of spirits, air to wit, and blood, from 

 the lungs and right sinuses of the heart, and in like 

 manner sends spirituous blood into the aorta, drawing 

 fuliginous vapours from thence, and sending them by 

 the arteria venosa into the lungs, whence spirits are at 

 the same time obtained for transmission into the aorta, 

 I ask how, and by what means, is the separation 

 effected ? and how comes it that spirits and fuliginous 

 vapours can pass hither and thither without admixture 

 or confusion. If the mitral cuspidate valves do not 

 prevent the egress of fuliginous vapours to the lungs, 

 how should they oppose the escape of air ? and how 

 should the semilunars hinder the regress of spirits from 

 the aorta upon each supervening diastole of the heart ? 

 and, above all, how can they say that the spirituous 

 blood is sent from the arteria venalis (pulmonary veins) 

 by the left ventricle into the lungs without any obstacle 

 to its passage from the mitral valves, when they have 

 previously asserted that the air entered by the same 

 vessel from the lungs into the left ventricle, and have 

 brought forward these same mitral valves as obstacles 

 to its retrogression ? Good God ! how should the 

 mitral valves prevent regurgitation of air and not of 

 blood ? 



Further, when they dedicate the vena arteriosa (or 

 pulmonary artery), a vessel of great size, and having the 

 tunics of an artery, to none but a kind of private and 

 single purpose, that, namely, of nourishing the lungs, 

 why should the arteria venalis (or pulmonary vein), 

 which is scarcely of similar size, which has the coats of 

 a vein, and is soft and lax, be presumed to be made for 

 many three or four, different uses ? For they will 

 have it that air passes through this vessel from the 



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