THE FROG-HEART 



6 9 



cardium. Do not grasp the heart with forceps or injure it in any way 

 by manipulation. 



On raising the ventricle the sinus venosus comes into view, receiv- 

 ing the two venae cavse superiores and the vena cava inferior ; above, 



Aortic trunk. 



Left auricle. _ 

 Pulmonary vein. 



Sinus venosus. 



Superior (ant.) vena cava. 

 Right auricle. 



Bulb of aorta. 

 Coronary sulcus. 



Pericardial fold with vein. 

 Vena cava inf. (post.). 



FIG. 58. Heart of frog from dorsal aspect (Gaupp). f. 



the sinus is continuous with, but marked off by a whitish line (sino- 

 auricular junction) from, the auricle, which is double and receives 

 on the left side the pulmonary vein ; the two auricles open into a 

 single ventricle. On the front the bulbus aortse are seen leaving the 



Ext. jugular vein. 



Superior (ant.) vena cava. 



Right pulmonary vein. 

 Sinus venosus. 



Innominate vein. 



Subclavian vein. 

 Right auricle. 



Bulb of aorta. 

 Coronary sulcus. 



Pericardial fold with vein. 



Ventricle apex. 

 FIG. 59. Heart of frog, seen from the right side (Gaupp). |. 



ventricle and dividing into two trunks, the right and left aortse, each 

 of which again soon divides into three branches. 



Notice that with each systole the venous part of the heart (sinus 

 venosus) contracts first ; its contraction is immediately followed by 

 that of the auricles, which contract together, and this by that of the 



