WILLIAM HARVEY. 



389 



tinuity of the arteries with the heart is destroyed 

 by section or ligature. The arteries fill, there- 

 fore, as bellows fill, not as bags are blown full. 



The ultimate ramifications of the arteries open 

 by anastomoses into those of the veins, all over 

 the body ; and the vivifying arterial blood thus 

 communicates its properties to the great mass of 

 blood in the veins. Under certain conditions, 

 however, the blood may flow from the veins to 

 the arteries, in proof of which Galen adduces the 

 fact that the whole vascular system may be emp- 

 tied by opening an artery. 



The two ventricles, the auricles, the pulmo- 

 nary vessels, and the aorta with its branches, are 

 conceived by the Greek anatomist to be an ap- 

 paratus superadded to the veins, which he re- 

 gards as the essential foundation and the most 

 important part of the whole vascular system. 

 No portion of Galen's doctrines has been more 

 sharply criticised than his persistent refusal to 

 admit that the veins, like the arteries, take their 

 origin in the heart, and his advocacy of the view 

 that the fons et origo of the whole venous system 

 is to be sought in the liver. Here, however, I 

 must remark that it is only those who are prac- 

 tically ignorant of the facts who can fail to see 

 that Galen's way of stating the matter is not only 

 anatomically justifiable, but that, until the true 

 nature of the circulation was understood, and 

 physiological considerations overrode those based 

 upon mere structure, there was much more to be 

 said for it than for the opposite fashion. 



Remembering that what we call the right 

 auricle was, for Galen, a mere part of the vena 

 cava, it is impossible not to be struck by the 

 justice of his striking comparison of the vena 

 cava to the trunk of a tree, the roots of which 

 enter the liver as their soil, while the branches 

 spread all over the body. Galen remarks that the 

 existence of the vena portte, which gathers blood 

 from the alimentary canal, and then distributes 

 it to the liver, without coming near the heart, is 

 a fatal objection to the view of his opponents, 

 that all the veins take their rise in the heart ; 

 and the argument is unanswerable, so far as the 

 mere anatomical facts are concerned. 



Nothing could have appeared more obvious 

 to the early anatomists than that the store of 

 nutriment carried by the vena porta; to the liver 

 was there elaborated into blood, and then, being 

 absorbed by the roots of the venous system, was 

 conveyed by its branches all over the body. The 

 veins were thus the great distributors of the 

 blood ; the heart and arteries were a superadded 

 apparatus for the dispersion of a " pneumatized " 



or vivified portion of the blood through the ar- 

 teries ; and this addition of " pneuma," or vivifi- 

 cation, took place in the gills of water-breathing 

 animals and in the lungs of air-breathers. But, 

 in the latter case, the mechanism of respiration 

 involved the addition of a new apparatus, the 

 right ventricle, to insure the constant flow of 

 blood through these organs of " pneumatization." 



Every statement in the preceding paragraphs 

 can be justified by citations from Galen's works; 

 and, therefore, it must be admitted that he had a 

 wonderfully correct conception of the structure 

 and disposition of the heart and vessels, and of 

 the mode in which the ultimate ramifications of 

 the latter communicate, both in the body gener- 

 ally and in the lungs ; that his general view of the 

 functions of the heart was just ; and that he knew 

 that blood passes from the right side of the heart, 

 through the lungs, to the left side, and undergoes 

 a great change in quality, brought about by its 

 relation with the air in the lungs, in its course. 

 It is unquestionable, therefore, that Galen, so far, 

 divined the existence of a "pulmonary circula- 

 tion," and that he came near to a just conception 

 of the process of respiration ; but he had no ink- 

 ling even of the systemic circulation ; he was 

 quite wrong about the perforation of the septum ; 

 and his theory of the mechanical causes of the 

 systole and diastole of the heart and arteries was 

 erroneous. Nevertheless, for more than thirteen 

 centuries, Galen was immeasurably in advance of 

 all other anatomists ; and some of his notions, 

 such as that about the active dilatation of the 

 walls of the vessels, have been debated by physi- 

 ologists of the present generation. 



No one can read Galen's works without being 

 impressed by the marvelous extent and diversity 

 of his knowledge, and by his clear grasp of those 

 experimental methods by which, alone, physiolo- 

 gy can be advanced. It is pathetic to watch the 

 gropings of a great mind like his around some 

 cardinal truth, which he failed to apprehend 

 simply because he had not in his possession the 

 means of investigation which, at this time, are 

 in the hands of every student. I have seen 

 learned disquisitions on the theme, Why did the 

 ancients fail in their scientific inquiries ? I know 

 not what may be the opinion of those who are 

 competent to judge of the labors of Euclid, or of 

 Hipparchus, or of Archimedes; but I think that 

 the question which will rise to the lips of the bio- 

 logical student, fresh from the study of the works 

 of Galen, is rather, How did these men, with their 

 imperfect appliances, attain so vast a measure of 

 success ? In truth, it is in the Greek world that 



