JACQUES LOEB 243 



Cs acts also somewhat like K but still less weakly than Rb. Only- 

 one series of experiments was made in an attempt to replace K by 

 Cs, and this series proved that in 2 cc. of m/2 CsCl mixture + 19 cc. 

 of natural sea water + 4 cc. of m/2 Li mixture swimming larvae could 

 be obtained. When no sea water was replaced by CsCl, 2 cc. of the 

 Li mixture in 25 cc. was the maximum which still permitted the 

 development of larvae. 



These results show that the toxic effects of Li, which occupies in 

 the periodic table a position on one side of NaCl, are mitigated by the 

 addition of ions like K, Rb, and Cs, occupying a position on the other 

 side of Na. A mixture of Li and K ions in proper proportions acts 

 more like a solution of Na ions than do the Li ions alone. 



TABLE v. 



Maximal Amount of Li Mixture Permitting Formation of Swimming Larvce. 



It should be taken into consideration that in these experiments the 

 balance between monovalent and bivalent cations was not disturbed. 



If we replace a smaller or larger percentage of the Na ions contained 

 in sea water by Mg or by Ca ions the toxicity of LiCl is not dimin- 

 ished. This is probably due to the fact that the quantity of Ca or 

 Mg required for balancing the monovalent cations is naturally present 

 in the sea water. 



The antagonism between LiCl and KCl can also be demonstrated 

 in the eggs of Fundulus. When newly fertilized eggs of Fundulus are 

 put into m/5 LiCl all the eggs are dead before an embryo is formed. 

 If, however, the m/5 solution of LiCl also contains a small quantity 

 of RbCl or of KCl, as many as 20 per cent of the eggs live long enough 

 to form embryos. When, however, the m/5 LiCl solution contains 

 NaCl not a single embryo is formed. CsCl also gives a positive effect. 

 The m/5 LiCl solution was made up in distilled water and in different 



