750 STUDIES IN GENERAL PHYSIOLOGY 



body, e. g., oxalic acid, or others. The necessary outcome 

 would be muscular twitchings. In that case the administra- 

 tion of calcium salts might cure the disease. 



2. In a recent paper I have shown that the antitoxic 

 effects calcium produces when added to a pure NaCl solution 

 are a function of its valency and the sign of its charge, inas- 

 much as similar effects can be produced by other bivalent or 

 trivalent kations (e. g., Mg, Sr, Ba, Zn, Fe, Co, Pb, Al, Cr), 

 but not by bivalent or trivalent anions. 1 The question arises 

 whether or not the inhibiting effects of Ca ions in the case 

 of rhythmical contractions of muscles are also a function of 

 the valency and electrical charge of the Ca ion. My earlier 

 experiments were not opposed to such a conclusion. I had 

 found that in f solutions 2 of LiCl, NaCl, KbCl, and CsCl 

 rhythmical contractions occur, while small amounts of the 

 chlorides of Ca, Mg, Sr inhibit these contractions. I have 

 since continued these experiments, with the following results : 

 When we put a muscle (the gastrocnemius of the frog was 

 used in these experiments) into a ^ sodium-acetate solu- 

 tion, the twitchings of the muscle begin at once. The addi- 

 tion of from 3 to 4 c.c. of a m CaCl 2 solution to 100 c.c. of a 

 sodium-acetate solution absolutely suppresses all twitch- 

 ings. But even half the amount suffices for practical pur- 

 poses, inasmuch as in this case only a few beats occur at the 

 beginning. MgCl 3 and SrCl 2 act like CaCl 2 . But BaCl 2 

 acts altogether differently. An addition of 5 c.c. of a m 

 solution of BaCl 2 to 10 c.c. ^ sodium-acetate solution not 

 only does not stop the rhythmical contractions, but makes 

 them more powerful. Instead of the rapid and rather weak 

 fibrillary twitchings which occur in a ^ sodium-acetate 

 solution, more tetanic and energetic contractions occur when 

 Bad 2 is added. I then tried whether the muscle is able to 



1 Part II, p. 708. 



2 By a solution is meant a solution which contains 1 gram-molecule in 8 liters. 



