74 INTRODUCTION 



and in the latter or right ventricle, for the blood? The same 

 arrangement cannot be held fitted to favour or impede the motion 

 of the blood and of spirits indifferently. 



3. And when we observe that the passages and vessels are 

 severally in relation to one another in point of size, viz., the 

 pulmonary artery to the pulmonary veins; why should the one 

 be destined to a private purpose, that of furnishing the lungs, 

 the other to a public function? 



4. And as Realdus Columbus says, is it probable that such 

 a quantity of blood should be required for the nutrition of 

 the lungs; the vessel that leads to them, the vena arteriosa or 

 pulmonary artery being of greater capacity than both the iliac 

 veins? 



5. And I ask, as the lungs are so close at hand, and in con- 

 tinual motion, and the vessel that supplies them is of such dimen- 

 sions, what is the use or meaning of this 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 draws materials for 

 the formation of spirits, air 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 there, and 

 sending them by the pulmonary vein 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? Above 

 all, how can they say that the spirituous blood is sent from the 

 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 the regurgitation of 

 air and not of blood ? 





