INTRODUCTION. 15 



there for the same end, of preventing here the egress, there 

 the regurgitation of the blood ? 



2. And again, when we see that these structures, in point of 

 size, form, and situation, are almost in every respect the same in 

 the left as in the right ventricle, wherefore should it be main- 

 tained that things are here arranged in connexion with the egress 

 and regress of spirits, there, i.e. in the right, of blood. The same 

 arrangement cannot be held fitted to favour or impede the motion 

 of 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; wherefore should the 

 one be imagined destined to a private or particular purpose, 

 that to wit, of nourishing the lungs, the other to a public and 

 general function? 



4. And, as Realdus Columbus says, how can it be conceived 

 that such a quantity of blood should be required for the nutri- 

 tion of the lungs ; the vessel that leads to them, the vena arte- 

 riosa or pulmonary artery being of greater capacity than both 

 the iliac veins ? 



5. And I ask further ; as the lungs are so close at hand, and 

 in continual motion, and the vessel that supplies them is of 

 such dimensions, what is the use 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 cuspi- 

 date 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 



