114 CIRCULATION OF THE BLOOD. 



greater space, like milk or honey set upon the fire. For were 

 the blood which is thrown from the left ventricle of the heart 

 into the arteries, fermented into any such frothy and flatulent 

 fluid, so that a drop or two distended the whole cavity of the 

 aorta; unquestionably, upon the subsidence of this fermenta- 

 tion, the blood would return to its original quantity of a few 

 drops ; (and this, indeed, is the reason that some assign for the 

 usually empty state of the arteries in the dead body ;) and so 

 should it be with the arterial blood in the cup, for so it is with 

 boiling milk and honey when they come to cool. But if in 

 either basin you find blood nearly of the same colour, not of 

 very different consistency in the coagulated state, forcing out 

 serum in the same manner, and filling the cups to the same 

 height when cold that it did when hot, this will be enough 

 for any one to rest his faith upon, and afford argument enough, 

 I think, for rejecting the dreams that have been promulgated 

 on the subject. Sense and reason alike assure us that the 

 blood contained in the left ventricle is not of a different nature 

 from that in the right. And then, when we see that the mouth 

 of the pulmonary artery is of the same size as the aorta, and 

 in other respects equal to that vessel, it were imperative on us to 

 affirm that the pulmonary artery was distended by a single drop 

 of spumous blood, as well as the aorta, and so that the right 

 as well as the left side of the heart was filled with a brisk or 

 fermenting blood. 



The particulars which especially dispose men's minds to 

 admit diversity in the arterial and venous blood are three in 

 number : one, because in arteriotomy the blood that flows is of 

 a more florid hue than that which escapes from a vein ; a second, 

 because in the dissection of dead bodies the left ventricle of 

 the heart, and the arteries in general, are mostly found empty; 

 a third, because the arterial blood is believed to be more spi- 

 rituous, and being replete with spirit is made to occupy a much 

 larger space. The causes and reasons, however, wherefore all 

 these things are so, present themselves to us when we ask after 

 them. 



1st. With reference to the colour it is to be observed, that 

 wherever the blood issues by a very small orifice, it is in some 

 measure strained, and the thinner and lighter part, which usu- 

 ally swims on the top and is the most penetrating, is emitted. 



