IgIo] LIPMAN—LACK OF ANTAGONISM IN SALTS 45 
on normally, but with a slight increase of CaCl, the contractions 
are inhibited, and when 5°¢ of a 0.375m solution of CaCl, are added, 
they are completely suppressed. On the other hand, when the margin 
of the fish,- containing the sense organs and the central nervous 
system, is cut off, CaCl, exercises a stimulating action on the isolated 
center of Polyorchis and contractions go on normally; but when 
MgCl, is added to the solution in the ratio of 4 parts MgCl, to 1 
part CaCl,, the stimulating action of the CaCl, is suppressed and 
contractions cease. In both cases, therefore, there is evidence of a 
definite antagonism between calcium and magnesium. LILLIE” 
also proved the existence of antagonism between the two salts when 
he found that the ciliary activity of the larvae of Arenicola would 
g0 on normally for some time in a mixture of approximately 4 parts 
MgCl, to x part CaCl,, whereas it would cease immediately if either 
of the salts at the same concentration was present alone. The same 
investigator found in other work that calcium salts inhibit the spon- 
taneous contractility of the swimming plate in ctenophores, when 
added to solutions made up of go parts by volume NaCl and ro parts 
MgCl,. Only 2 volumes of CaCl, of the same concentration as the 
other salts inhibit movements of the swimming plate in the sodium 
and magnesium solution above described, while 4 volumes of CaCl, 
allow but little spontaneous movement. The latter is entirely inhib- 
ited by the addition of 8 volumes of the CaCl, solution. 
I wish to cite only one more case, which emphasizes by contrast 
most strongly the exceptional results obtained above in experiments 
with B. subtilis, and that is, the remarkable results obtained in a 
highly ingenious series of experiments recently carried out by MELT- 
ZER and AUER*3 on the antagonistic effect of calcium on the inhibitory 
elect of magnesium. The experiments were carried out on rabbits, 
and in one case on a monkey, and as a typical instance of the remark- 
able antagonistic effect between calcium and magnesium may be 
cited the first experiment of the series, in which about 13°° of an 
m/1 solution of MgCl, was injected subcutaneously into a rabbit. 
Less than one-half hour later there was produced general anaes- 
thesia, with all the attending symptoms, and a o.125m solution of 
'* Amer. Jour. Physiol. 5:56. 19or. 
"3 Amer. Jour. Physiol. 21:403. rg09. 
