1 8 On the Heart and Blood 



lungs into the left ventricle ; that fuliginous vapours 

 escape by it from the heart into the lungs ; and that 

 a portion of the spirituous or spiritualized blood is dis- 

 tributed by it to the lungs for their refreshment. 



If they will have it that fumes and air fumes flowing 

 from, air proceeding towards the heart are transmitted 

 by the same conduit, I reply, that nature is not wont to 

 institute but one vessel, to contrive but one way for 

 such contrary motions and purposes, nor is anything 

 of the kind seen elsewhere. 



If fumes or fuliginous vapours and air permeate this 

 vessel, as they do the pulmonary bronchia, wherefore 

 do we find neither air nor fuliginous vapours when we 

 divide the arteria venosa ? why do we always find this 

 vessel full of sluggish blood, never of air ? whilst in the 

 lungs we find abundance of air remaining. 



If any one will perform Galen's experiment of dividing 

 the trachea of a living dog, forcibly distending the lungs 

 with a pair of bellows, and then tying the trachea 

 securely, he will find, when he has laid open the 

 thorax, abundance of air in the lungs, even to their 

 extreme investing tunic, but none in either the pulmonary 

 veins, or left ventricle of the heart. But did the heart 

 either attract air from the lungs, or did the lungs 

 transmit any air to the heart, in the living dog, by so 

 much the more ought this to be the case in the 

 experiment just referred to. Who, indeed, doubts that, 

 did he inflate the lungs of a subject in the dissecting- 

 room, he would instantly see the air making its way by 

 this route, were there actually any such passage for it ? 

 But this office of the pulmonary veins, namely, the 

 transference of air from the lungs to the heart, is held 

 of such importance, that Hieronymus Fabricius, of 

 Aquapendente, maintains the lungs were made for the 

 sake of this vessel, and that it constitutes the principal 

 element in their structure. 



But I should like to be informed wherefore, if the 

 pulmonary vein were destined for the conveyance of 



