Muscuuar TwItcHINes 751 
beat in a pure BaCl, solution. It goes without saying that 
in pure solutions of MgCl,, CaCl,, and SrCl, a muscle does 
not show any rhythmical contraction. Ina ™” BaCl, solu- 
tion, however, the muscle beat for forty minutes; in a 
solution, for one and a half hours; in a 7 BaCl, solution, 
for over an hour; and in a 7 BaCl, solution, for about 
half an hour. The beats showed the same tetanic form char- 
acteristic of the presence of barium. The fact that the beats 
stop sooner in a % BaCl, solution than in a ™ solution 
is due to the poisonous effects of barium. The fact that the 
beats stop also very soon in a 7% BaCl, solution is due to 
the enormous absorption of water which occurs in such weak 
solutions.’ 
Similar facts were found for Ba(NO,), and Ba (HO),. 
The most striking fact is that the stimulating power of Ba 
salts is greater than that of the corresponding Na salts. 
In a 7% BaCl, solution the muscle may begin to beat in a 
few minutes and may continue to do so for half an hour. I 
have even occasionally noticed rhythmical contractions in a 
zz, BaCl, solution. But I have never noticed any rhyth- 
mical contractions of muscle in a #4 NaCl solution, and as 
a rule even in a % NaCl solution the twitchings begin only 
after a long latent period and last but a short time. 
Barium is, however, not the only bivalent kation whose 
chloride possesses a higher stimulating power than that of 
the chloride of univalent kations. It was found that the 
chlorides of the heavy metals are also capable of producing 
rhythmical twitchings or beats of muscles in much lower 
concentrations than those found effective in the case of NaCl 
or LiCl. In ,%, solutions of ZnCl, strong beats occurred, 
which, however, did not last long on account of the rapid 
imbibition of the muscle with water, as well as on account 
1The beats in BaCl, solution often do not begin at once, but after a latent period 
of from two to fifteen minutes. 
Digitized by Microsoft® 
