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 effect 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 in the resistance of the 

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



Fig. 11. — Curve to show the effect of a 

 ri&e of temperature from 0° C. to 38° C. upon 

 the height of contraction of frog's muscle. 

 The first maximiim at 9° C, the second at 

 28° C. Beyond 38° C. the muscle lost its 

 irritabUity and went into rigor mortis. 



JO' 2s- JO- Si' 37' Sr V 



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. 



