46G 



ANNALS NEW YORK ACADEMY OF SCIENCES 



NO ACTIVITY 



Ob 



10 



15 



20 



CA WILLIMOLCS PER LITER 



Figure 8. The respiration (as per cent of value in reference solution) of a frog sciatic nerve 

 increasing when the concentration of calcium chloride in bathing fluid is below 1.0 mM. There 

 is an appreciable increase at a concentration which is not low enough to initiate impulses. 



300 



50 

 Threshold 



Figure 9. Respiration of frog sciatic nerve in relation to threshold of a fibers in same nerve. 

 Changes produced by equilibration in isosmotic solutions containing 1.0, 0.5, and 0.25 mM CaCh. 

 Both respiration and threshold (rheobase) are expressed as per cent of their values (marked bj 

 solid square) in reference solution (containing 2.0 mM CaCh). 



Open circles : A nei-ve showing a small per cent change in respiration has a correspondingly small 

 per cent change in rheobase. 



Solid cu'cles : Another nerve, showing a large per cent change in respiration, has a large per 

 cent change in rheobase. 



