CHAPTER XVI 



PERFUSION OP HEART 



Perfusion of frog-heart. -Kill a large frog and expose the heart ; 

 remove the pericardium and cut through the pericardial ligament. 

 Very carefully raise the apex of the ventricle with a blunt instrument, 

 remembering that the least injury to the surface of the ventricle will 

 spoil it for this experiment. Make a free cut with scissors into the 

 auricles thus exposed, near to the sino-auricular junction ; insert the 

 scissors into the auricles and snip through their septum. Wash all 

 blood away with Ringer's solution. Place a ligature of wet cotton 

 round the auricles near their junction with the ventricles ; insert the 

 double perfusion Kronecker cannula (fig. 61,/') through the auricles 

 and into the ventricle, and tie it in firmly by means of the ligature ; 

 cut through the sinus, and remove the heart upon the cannula. 

 The inlet tube of the perfusion cannula is connected to a reservoir 

 (Mariotte bottle) containing about 100 c.c. Ringer's solution, and the 

 outlet tube conducts to a receptacle into which the fluid may flow 

 after passing through the heart. Whilst the heart is being fastened 

 over the cannula, let Ringer's fluid flow very slowly (drop by drop) 

 through the cannula so as to expel and keep all air out of the 

 cannula and heart. 



Now place the heart in the plethysmograph. The lower part of 

 the plethysmograph contains Ringer's solution : the upper part and 

 the tubes leading horizontally from it contain pure, moderately thin 

 paraffin oil. 1 Both stop-cocks are closed whilst the heart is inserted ; 

 then the one belonging to the bent tube is opened. If the reservoir of 

 Ringer's fluid be at a height of three or four inches above the heart, 

 the ventricle will soon begin to beat, and its changes in volume will 

 cause a movement of the oil to and fro in the open tube. If this tube 



1 Not olive oil. Ringer's solution may be substituted for oil in the plethys- 

 mograph, but for the piston-tube oil is required. 



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