424 THE DYNAMICS OF CARDIAC ACTION. 



data. As the cannula was tied directly into the artery, the 

 liquid could only reach the cavities through the foramina, while 

 in all experiments care was taken to avoid high pressures. In 

 the heart of the ox the endocardial depressions were found 

 "regularly larger in the auricles than in the ventricles," while 

 in the right auricle "they may," he states, "be provided with 

 thin, single valves, especially about the origin of the great veins." 

 In the left auricle the depressions are fewer in number and 

 unprovided with valves. "Foramina Thebesii are never absent 

 from the ventricles," says Dr. Pratt. "In the right ventricle, 

 which is especially well provided with them, the larger number 

 are seen upon the septal wall. It is often much more difficult 

 to find them in the left ventricle, although a diligent search is 

 never without a reward" . . . "structures, accessory to 

 these ventricular foramina, which might in any way serve the 

 office of valves I have not seen." . . . "On the injection 

 of the vessels of Thebesius with air by means of the blow-pipe 

 applied to the foramina, characteristic, fine, subendocardial 

 ramifications, which very frequently conduct the air into other 

 Thebesian systems, or even into the great coronary veins will 

 seldom fail to appear." The latter point is also sustained by 

 experimental evidence. 



The fact that the right side of the heart is endowed with 

 a more perfect system of canalization than the left is suggested 

 by the following remarks: "The ease with which injections 

 of air and blood could be made to demonstrate the connection 

 between the vessels of Thebesius and the coronary veins caused 

 me to doubt the opinion expressed by Langer that the foramina 

 Thebesii in the ventricles communicate with the veins by capil- 

 laries alone. To settle this point, I injected the coronary veins 

 of the ox with starch and celloidin masses, both too thick to 

 pass the capillaries, and found that even these emerged from 

 the foramina Thebesii. of the right ventricle. So intimate a 

 connection, however, between the coronary veins and the ves- 

 sels entering the left ventricle I have not yet been able to demon- 

 strate." The author also says: "By means of a very successful 

 corrosion preparation, made by injecting the veins of an ox- 

 heart with celloidin, I was able to trace the communication. 

 In this preparation the position of some of the foramina 



