186 PROCEEDINGS OF THE AMERICAN ACADEMY. 



ject SO thoroughly studied as the physiology of the Vagus, this most 

 important function has received such slight attention and is so imper- 

 fectly understood, may be due to the not less surprising circumstance, 

 that students of the physiology of the heart have in a peculiar manner 

 overlooked the more central parts of the organ, the very source of the 

 heart revolutions, viz. the large veins. Especially is this the case with 

 regard to the influence of nerves upon the heart. Most investigators 

 have contented themselves with observing simply the ventricle. Gas- 

 kell and Engelmann and Bayliss and Starling recorded systematically 

 the movements of the ventricle and the auricle : no one thus far has 

 studied the influence of nerves of cold-blooded animals upon ven- 

 tricle, auricle, and sinus, recording the movements of all these parts 

 at the same time. Knoll very recently did so with great skill in the 

 mammalian heart ; the conditions are there, however, much less favorable 

 for an analysis of the Vagus action, as it has Ijeen found by me to exist 

 in the case of the amphibian heart. By simply recording the movements 

 of the sinus alone under Vagus action, this part of the heart proves to be 

 capable of quite complicated forms of activity. The Vagus is able to dis- 

 sociate the movements of the large veins in a manner well adapted to 

 throw light upon the cause of the normal heart-beat. While the au- 

 ricles and ventricles undoubtedly perform the most important functions 

 in the mechanical work of maintaining the circulation, we have to look 

 upon these portions of the heart, as far as their rhythmical motions are 

 concerned, as under the control of influences proceeding from the large 

 veins. In regard to this point, the study by Engelmann of the muscular 

 properties of the sinus, published in 1896,* and Tigerstedt and Stromberg's 

 previous work on the same subject, are to be consulted. 



A second important point in which my experimental work differs from 

 that of my predecessors is, that I forsook the customary method of excis- 

 ing the heart with the adherent Vagus nerves. In both series of experi- 

 ments, in Holland as well as in America, I have been able to show that the 

 functions of the heart, and still more the normal action of the Vagus, are 

 injuriously affected by the least lack of normal nutrition. I have, therefore, 

 taken the greatest care, in employing the suspension method of Engelmann, 

 to attach the different parts of the heart to the recording levers in such a 

 way that the circulation through the heart and the body was interfered 

 with as little as possible. The slightest loss of blood is constantly followed 

 by changes in the force, and still more by changes in the conducting power 



* Pfliiger's Archiv., Band LXV. p. 109. 



