238 CHEMICAL CHARACTER OF POTASSIUM 



solutions corresponds to its purely chemical character; i.e., its position 

 in the periodic table (or rather to its atomic number and arrangement 

 of external electrons). 



II. The Resemblance in the Antagonistic Efects of the NH^ and K Ions. 



According to their physiological action the ions of the alkaline metals 

 can be arranged in two distinct groups, the one including Li and 

 Na, the other K, Rb, and Cs. The difference in the two groups is 

 noticeable in various phenomena. Isotonic solutions of LiCl and 

 NaCl will give rise to muscular twitchings while K CI, RbCl, and prob- 

 ably CsCl will not. Experiments on the egg of Fundulus show that 

 toxic solutions of salts with bivalent metals, such as MgCU or CaCl2, 

 can be rendered less toxic by the addition of KCl, RbCl, or CsCl, 

 but not or practically not by the addition of NaCl or LiCl.^ It is 

 known that the NH4 ion resembles in its chemical behavior the K 

 ion more closely than it does the sodium ion, and Langmuir^ has 

 utilized this fact in support of his theory of the cubical atom. If it 

 be true that the physiological action of K depends upon its chemical 

 character, the close resemblance between the chemical character of 

 NH4 and K should express itself in phenomena of antagonism. NH4CI 

 is generally very toxic for cells but it can be used with good effect in 

 experiments on the egg of Fundulus which is surrounded by a rather 

 impermeable membrane. In experiments on Fundulus it can be 

 shown that the antagonistic action of the NH4 ion is like that of the 

 members of the K group and not like that of the members of the Na 

 group. 



When newly fertilized eggs of Fundulus are put into a 5 m/32 solu- 

 tion of CaCl2 practically no egg {i.e. less than 2 per cent of the eggs) 

 can form an embryo. When the 5 m/32 CaCl2 solution is made up 

 in solutions of different chlorides instead of in H2O it is found that in 

 LiCl and NaCl the toxicity of the CaCl2 solution is not diminished. 

 When, however, the 5 m/32 CaCU solution is made up in KCl, RbCl, 

 CsCl, or NH4CI a considerable percentage of the eggs can develop 

 into embryos as is shown in Table I. 



3 Loeb, J., /. Biol. Chem., 1914, xix, 431. 



^ Langmuir, I., /. Am. Chem. Soc, 1920, xlii, 274. 



