HIS WORKS. lix 



and had he said nothing more than we find in single detached 

 sentences or paragraphs of his book, he must have been re- 

 garded as having gone a great length in the right direction. 

 The blood, he says, once it has entered the right ventricle 

 from the vena cava, can in no way again get back ; for the 

 tricuspid valves are so placed that whilst they give a ready pas- 

 sage to the stream inwards, they effectually oppose its return. 

 The blood continuing to advance from the right ventricle into 

 the vena arteriosa or pulmonary artery, once there cannot flow 

 back upon the ventricle, for it is opposed by the sigmoid valves 

 situate at the root of the vessel. The blood, therefore, agitated 

 and mixed with the air in the lungs, and having thus 

 in some sort acquired the nature of spirit, is carried by the 

 arteria venosa or pulmonary vein into the left ventricle, from 

 whence, being received into the aorta, it is, by the ramifica- 

 tions of this vessel, transmitted to all parts of the body. 



This much taken by itself looks very like an exposition of 

 the circulation of the blood as understood at the present time, 

 though we still see that the blood must be made to participate 

 in the nature of spirit before it enters the arteries, and is not 

 the blood which is contained in the veins, and which nourishes 

 the body ; but when we go farther and turn to other parts of his 

 writings, AVC see that Columbus could never have conceived any 

 proper idea of the circulation. For example, he continues, with 

 Galen, to regard the liver as the origin of all the veins. The 

 vena portse, he says, arising by innumerable roots from the con- 

 cavity of the liver, proceeds to carry blood from this organ by 

 different branches to the stomach, spleen, and intestines, to the 

 end that it may convey nourishment in the first case, black bile 

 in the second, and in the third serve a double function viz. 

 supply nourishment to the intestines at once, and by a kind 

 of imbibition, obtain nutritive matter, which is forthwith sent 

 back to the liver for elaboration into blood. The vena cava 

 again, he describes as arising from the convex aspect of the 



