30 



THE PHYSIOLOGY OF MUSCLE AND NERVE. 



for the muscle at room temperatures, causes greater and greater 

 contractions up to a certain maximum, which is reached at about 

 5 to 9 C. As the temperature rises beyond this point the con- 



Fig. 10. Curve showing the effeet of temperature. The temperatures at which the 

 contractions were obtained are indicated on the figure. In this experiment a large resis- 

 tance was introduced into the secondary circuit so that changes va the resistance of the 

 muscle itself due to heatiog could not affect the strength of the stimulus. 



Fig. 11. Curve to show the effect of a 

 rioe of temperature from C. to 38 C. upon 

 the height of contraction of frog's muscle. 

 The first maximum at 9 C. the second at 

 28 C. Beyond 38 C. the muscle lost its 

 irritability and went into rigor mortis. 



Fig. 12. Curve to show the effect 

 of a rise of temperature from 5 C. to 

 39 C. upon the duration of contraction 

 of frog's muscle. The relative dura- 

 tions at the different temperatures are 

 represented by the height of the cor- 

 responding ordinates. 



