THE) CIRCULATION. 



169 



and in the other figure the upper curve of the cardiogram 

 represents the events in the auricle, the lower those in the 



\ . - 



Fig. 82. CARDIOGRAMS OF THE RIGHT AURICLE (o d) AND RIGHT VENTRICLE (v d) TAKEN 



ON AN EXPOSED HUMAN HEART. (After Franck.) 



Vertical lines indicate same instants of time. 



ventricle. The two are so arranged that vertical lines con- 

 nect the same instants of time. 



The cardiogram of the horse in figure 81 was obtained 

 by pushing a tube provided with a rubber bulb at its end 

 through the jugular vein in the neck into the right auricle, 

 and a second such tube through the auricle into the ven- 

 tricle. The relative compressions of the bulbs in the diastole 

 and systole were then recorded with a tambour and the 

 curves obtained. Such a tambour consists essentially of a 

 light metallic box, covered on one side with a thin piece of 



Fig. 83. A TAMBOUR. 

 T, the metal box ; H, the recording lever resting on the rubber membrane. 



stretched rubber. On this rubber rests the recording lever. 

 The metallic box is connected with a tube from the heart, 



