EFFECT OF TEMPERATURE ON PULSATION 331 



shifting of the pulsations upwards. This movement of 

 contraction goes on till there is a complete arrest brought 

 about by heat rigor. 



Summary 



The effect of lowering of temperature on the rhythmic 

 pulsation of Desmodium gyrans is similar to that on the 

 pulsation of frog's heart. Lowering of temperature enhances 

 the amplitude but reduces the frequency of pulsation of 

 both. 



The pulsation of Desmodium leaflet is arrested at the 

 minimum temperature of about 17 C. Arrest takes place 

 at systole ; gradual warming revives the pulsation, which 

 undergoes a staircase increase with enhancing diastolic 

 expansion. 



Rise of temperature induces enhanced frequency and 

 diminished amplitude of pulsation. 



During rise of temperature to about 43 C. there is a 

 tendency of arrest towards diastole. The systolic con- 

 traction undergoes continuous diminution during rise of 

 temperature. 



During the fall of temperature there is a gradual enhance- 

 ment of systolic contraction. 



The temperature maximum at which arrest of pulsation 

 takes place may be as high as 45 C. Above this temperature 

 there is a tendency to contraction and permanent arrest 

 under heat-rigor. 



