10 
Scientific Proceedings (40). 
6 (53i) 
The role of the concentration of hydroxylions in the antago- 
nistic action of K and Ca upon Na. 
By JACQUES LOEB. 
[From the Rockefeller Institute for Medical Research, New York.] 
It has been proved during the last years that quite generally in 
animals, plants and bacteria, a poisonous solution of NaCl can be 
rendered harmless through the additon of small quantities of 
CaCl 2 +KCl. A number of years ago I published results of ex- 
periments which indicated that the r61e of Ca in these experiments 
was fundamentally different from that of K. When fertilized eggs 
of Fundulus were put into m/2 solution of NaCl which killed the 
eggs in a comparatively short time it was found that small quan- 
tities of CaCl 2 or certain other salts with a bivalent metal rendered 
the solution comparatively harmless; while the same cannot be 
accomplished through the addition of KC1, LiCl or NH 4 C1 to 
the mj 2 solutions of NaCl. 
Recently I was able to show this difference in the action of Ca 
and K in a rather striking way. The fertilized eggs of Strongy- 
locentrotus were put in the following four solutions: first NaCl; 
second, Na+K; third, Na+Ca; fourth, Na+Ca+K. The ex- 
periments were made with neutral as well as with acid and alkaline 
solutions. It was found that in the neutral and acid solution 
the antagonistic effect of K prevailed over that of Ca, which was 
very slight; while in alkaline solutions the antagonistic effect of 
Ca was comparatively strong, while that of K was rather slight. 
If newly fertilized eggs of the sea urchin are put into a mixture 
of NaCl+KCl, one finds that if the solution is neutral, the eggs 
segment rather normally and they may reach the 64 cell stage. 
If, however, the solution is made faintly alkaline the eggs are 
cytolized without segmenting. 
If, however, the similar experiment is made with a mixture of 
Na+Ca one finds that the eggs segment better and further when the 
solution is faintly alkaline than when it is neutral. To give an 
example: In a neutral mixture of Na+Ca in one experiment only 
40 per cent, of the eggs of Arbacia segmented and these did not go 
