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.’ 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 ™ solutions’ of LiCl, NaCl, RbCl, 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 am CaCl, 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, and SrCl, act like CaCl,. But BaCl, 
acts altogether differently. An addition of 5 cc. of a m 
solution of BaCl, 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 
BaCl, is added. I then tried whether the muscle is able to 
1Part II, p. 708. 
2By a } solution is meant a solution which contains 1 gram-molecule in 8 liters. 
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