IONS AND SALT ACTION. 75 



animal forms by the aid of methods adhering more or less closely to the 

 above. 



Certain ions or salts have an antagonistic action upon the animal 

 organs. NaCl has in general a beneficial influence upon animal tissues. 

 Nevertheless, pure NaCl solutions can have a poisonous action, for example 

 upon frog muscles. In such cases the toxic action is arrested by the 

 addition of small quantities of other salts, namely K and Ca salts. Upon 

 this depends the use, in experiments with animal organs, of the so-called 

 KIXGER-LOCKE 1 solution, which contains in a liter about the following 

 substances: 6.5-9.5 grams NaCl + 0.2 grams KC1 + 0.2-0.3 gram CaCl 2 , 

 and also 0.1 gram NaHCO 3 . The experiments of LOEB with the fertilized 

 eggs of the Fundulus heteroclitus are very interesting. These eggs 

 develop just as well in a remarkable manner in water free from salt as 

 in sea-water, and are completely insensible to osmotic influence. But 

 if the fertilized eggs are placed in a NaCl solution of the same osmotic 

 pressure as the sea-water they die; the toxicity of the NaCl solution 

 can be arrested by small quantities of nearly any salt with polyvalent 

 cations. Not only the salts of the alkaline earths, but also those of the 

 heavy metals can neutralize the toxicity of the NaCl in proper concen- 

 tration. 2 Wo. OSTWALD has carried on similar experiments with 

 Gammarus pulex. 3 



1 Journ. of Physiol., 18, 318, 1895. 



2 Pfliiger'S Arch., 88, 68, 1901. 



3 Ibid., 106, 568, 1905. 



