CH. IX.] 



THE SIMPLE MUSCLE CUKVE 



99 



tures on to the muscle before taking its curve. Fig. 120 shows the 

 result of such an experiment. Too great heat (above 42 C.) induces 

 heat rifjor, due to the coagulation of the muscle proteins. 



FIG. 120. Effect of temperature on the simple niuscie curve. The various temperatures are marked 

 on the curves. P is the point of stimulation ; and the time-tracing again indicates hundredths of 

 a second. 



5.. Effect of veratrine. If this is injected into the frog before the 

 muscle-nerve preparation is made, the very remarkable result seen 



Fio. 121. Veratrine curve, taken on a very slowly travelling cylinder; the time-tracing indicates 

 seconds, not hundredths of a second as in the previous diagrams. 



in fig. 121 is produced on stimulation; there is an enormous 



