40 MOTION OF THE 



the blood is sent through the lungs, that it may he tempered 

 by the air that is inspired, and prevented from boiling up, and so 

 becoming extinguished, or something else of the sort. But to 

 determine these matters, and explain them satisfactorily, were 

 to enter on a speculation in regard to the office of the lungs and 

 the ends for which they exist ; and upon such a subject, as well 

 as upon what pertains to eventilation, to the necessity and use 

 of the air, &c., as also to the variety and diversity of organs that 

 exist in the bodies of animals in connexion with these matters, 

 although I have made a vast number of observations, still, lest 

 I should be held as wandering too wide of my present purpose, 

 which is the use and motion of the heart, and be charged with 

 speaking of things beside the question, and rather complicating 

 and quitting than illustrating it, I shall leave such topics till I 

 can more conveniently set them forth in a treatise apart. And 

 now, returning to my immediate subject, I go on with what yet 

 remains for demonstration, viz., that in the more perfect and 

 warmer adult animals, and man, the blood passes from the right 

 ventricle of the heart by the vena arteriosa, or pulmonary artery, 

 into the lungs, and thence by the arterise venosse, or pulmonary 

 veins, into the left auricle, and thence into the left ventricle of 

 the heart. And, first, I shall show that this may be so, and 

 then I shall prove that it is so in fact. 



CHAPTER VII. 



THE BLOOD PERCOLATES THE SUBSTANCE OP THE LUNGS FROM 

 THE BIGHT VENTRICLE OF THE HEART INTO THE PULMONARY 

 VEINS AND LEFT VENTRICLE. 



THAT this is possible, and that there is nothing to prevent 

 it from being so, appears when we reflect on the way in which 

 water percolating the earth produces springs and rivulets, or when 

 we speculate on the means by which the sweat passes through the 

 skin, or the urine through the parenchyma of the kidneys. It 

 is well known that persons who use the Spa waters, or those of 

 La Madonna, in the territories of Padua, or others of an acid- 

 ulous or vitriolated nature, or who simply swallow drinks by the 

 gallon, pass all off again within an hour or two by urine. Such 



