CHAPTER X. 



Perfusion of frog-heart. Expose the heart of 

 a large pithed frog ; remove the pericardium and 

 cut through the pericardial ligament. Raise the 

 apex of the ventricle with a blunt hook ; make a 

 free cut with scissors into the auricles thus ex- 

 posed, near to the sino-auricular junction ; insert 

 the scissors into the auricles and snip through 

 their septum. Wash all blood away with salt 

 solution. Place a loop of cotton around the auri- 

 cles near to their junction with the ventricles ; in- 

 sert the double perfusion cannula of the heart 

 plethysmograph (Fig. 45) through the auricles 



4 _- Perfusion cannula 

 ("natural size). 



Beaker for overflow 



Perfusion cannula 



Heart tied on perfusion 



cannula 



FIG. 45. FROG-HEART PLETHYSMOGRAPH. 



