1224 



interval, nor at an interval of 0.0063", whilst lengthening to 0.0115" 

 made the degree of summation 0.05. The muscle having been cooled 

 down to 2° the summation was at a stimulation-interval of 0.0115" 

 and 0.0157", whilst it became 0.037 at an interval of 0.021". 



The other experiments gave similar results (vSee page 1223). 



Refrigeration therefore lengthens the refractory stage. 



The temperature from which we starled being an arbitrary one 

 the effect of heating was also investigated. 



From the following values 



it appeared that heating shortens the refractory stage. 



Carbonic acid. 



In the moist chamber, used in the foregoing expeiiraents carbonic 

 acid was led; for the rest the installation was the same. Though 

 carbonic acid gas will act upon the muscle but very slowly from 

 outside, it may yet be assumed that within not too long a time it 

 will have a marked influence on the condition of the muscle, since 

 it prevents the carbonic acid formed by function in the muscle, 

 from leaving it. 



The following is experiment 59. 



At a stimulation-interval of 0.0042" the muscle originally gives a 

 summation of 0.06. After having been surrounded by carbonic acid gas 

 for 15', it shows no summation at this interval, whilst summation 

 becomes 0.06 again, if the stimulus-interval is lengthened to 0.0068". 



