426 THE DYNAMICS OF CARDIAC ACTION. 



steady, stream of venous blood issued from them." Under the 

 same conditions the descending branch of the left coronary 

 artery was opened. "No flow of blood occurred from the artery, 

 although there was a free escape from an incision in an ac- 

 companying vein." In still another experiment the trunks of 

 both coronary arteries were ligated and the ligature around 

 the ventricles omitted. "The supply-cannula was tied into the 

 ventricle through the aorta. On the introduction of blood 

 the left ventricle alone began to beat strongly and regularly 

 . . . the blood found its way in part into the right ven- 

 tricle, coming of necessity through the walls. . . ." The 

 blood from the left ventricle had thus found its way into the 

 right one. Finally, he refers to the striking analogy which 

 this nutritional system presents to that of the frog and cat. 

 In the frog the heart is almost entirely nourished "through 

 the branching passages that carry the blood from the interior 

 of the heart nearly to the pericardial surface." 



On the strength of all this evidence, Dr. Pratt concludes 

 (giving only the features that bear directly upon the question 

 we are analyzing) that: "1. The vessels of Thebesius open 

 from the ventricles and auricles into a system of fine branches 

 that communicate with the coronary arteries and veins by 

 means of capillaries, and with the veins but not with the 

 arteries by passages of somewhat larger size. 2. These vessels 

 are capable of bringing from the ventricular cavities to the 

 heart-muscle sufficient nutriment to maintain long-continued, 

 rhythmic contractions. 3. The heart may also be effectively 

 nourished by means of a flow of blood from the auricle back 

 into the coronary sinus and veins." The author concludes 

 with the very appropriate remark: "It is evident that the nu- 

 trition through the vessels of Thebesius and the coronary veins 

 must modify in no slight degree the existing views of the 

 nutrition of the mammalian heart, and of the manner in which 

 infarction of the heart takes place." The clinical features of 

 this question will be considered elsewhere. 



Viewed from our standpoint, the vessels of Thebesius are 

 more concerned with the dynamics of the heart than with the nu- 

 trition of this organ, though the latter function is not to be 

 ignored, particularly in the sense emphasized by Pratt: i.e., 



