104 



Scientific Proceedings (33). 



and to rennin. Trypsin was tested by the casein method of Gross 

 and the rennin was determined by the method of Blum and Fuld 

 with sh'ght modifications which will not be discussed here. Both 

 ferments were shaken at room temperature, and at 33°C.; also the 

 influence upon the results of different rates of shaking and of 

 changes in other conditions were investigated. We shall, however, 

 state here only that the destructive effect of shaking upon trypsin 

 and rennin is, as for pepsin, distinctly increased by increasing the 

 rate of shaking and by increasing the temperature at which the 

 shaking is carried on. There is a pronounced difference in the 

 resistance to shaking between pepsin and trypsin under the condi- 

 tions thus far studied, the latter being more readily affected. The 

 destructibility of rennin runs practically parallel with that of pepsin. 



52 (390) 



The influence of sodium and calcium upon direct and indirect 

 muscle irritability and their mutual antagonistic actions. 



By DON R. JOSEPH and S. J. MELTZER. 



\_Froin the Department of Physiology and Pharmacology of the 

 Rockefeller Institute for Medical Research, New York.'\ 



By the researches of Kiihne, Biedermann, Ringer, Loeb, and 

 many others, it is established that solutions of sodium chloride 

 cause rhythmical movements of the muscles of the frog, and that 

 the addition of a small quantity of calcium will stop them. By 

 the researches of Locke, Carslaw, Gushing, Poljakoff and Overton, 

 it is further established that solutions of sodium chloride abolish 

 indirect irritability, and that the addition of a small dose of calcium 

 restores it. There has been very little work done on the primary 

 effect of calcium upon the direct and indirect irritability of the 

 skeletal muscles of the frog and there are practically no researches 

 on the action of sodium upon the primary effects of calcium. 



In our experiments, sodium and calcium chlorides were em- 

 ployed in M/io solutions and were introduced by infusion through 

 the abdominal aorta according to the method described by 

 Gushing.' The graphic records were obtained from the gastro- 



* Gushing : American four, of Physiol., 1902, vi, 77. 



