ION-PEOTEID COMPOUNDS 551 



This result agrees with our theory. But in order to 

 make the proof complete we must be able to show that an 

 addition of certain other ions annihilates the poisonous 

 effects of a pure NaCl solution. I tried the following solu- 

 tions upon Fundulus: 



(1) 96 c.c. | n NaCl + 4 c.c. Y n MgCl 2 



(2) " " " +4 c.c. fnKCl 



(3) " " +4 c.c. Y 



In each of these solutions the fish died in less than or in 

 about twenty-four hours. After this experiment two salts 

 were tried in combination with NaCl, and the following 

 solutions were prepared: 



(1) 96 c.c. 1 n NaCl + 2 c.c. Y n MgCl 2 + 2 c.c. V n CaCl 2 



(2) " " " + " + " I n KC1 



(3) " " " + " VnCaCl 2 + " InKCl 



This time the result was very striking. In the first of 

 these three solutions the animals lived less than thirty hours, 

 in the second a few hours longer; in the third they were 

 still alive ten days later when I discontinued the experiment. 

 Thus we see that the poisonous effects of the NaCl solution 

 really disappear if we add a small amount of K and Ca ions, 

 which makes the proof of our theory complete. 



In the pure NaCl solutions we have to deal with two ions, 

 Na and Cl ions. Are both equally responsible for the 

 poisonous effect? The fact that KC1 and CaCl 3 prevent the 

 poisonous effects of the NaCl solution proves that the metal 

 ions are of greater importance than the Cl ions. 



I stated above that Fundulus stands the addition of rather 

 large quantities of NaCl to sea-water. I tried to determine 

 whether K and Ca ions were able to counteract even larger 

 doses of NaCl than are contained in a f n NaCl solution. A 

 number of young Funduli were put into the following solu- 

 tions : 



