552 STUDIES IN GENERAL PHYSIOLOGY 



(1) 101) c.c. J^ 



(2) 96 " " +4 c.c. InKCl 



(3) 96 " +4 " YwCaClj 



(4) 96 " +2 " V-wCaCl 2 +2c.c.|MKCl 



(5) 93 " " +5 " VHCaCl a +2c.c. 1-nKCl 



In solutions 1 and 2 the animals died in less than two hours. 

 In solution 3 the animals were found dead the next morning. 

 In solution 4 the animals died within three days; and in 

 solution 5 one animal was still alive at the end of the third 

 day when the experiment was discontinued. The presence 

 of small amounts of K and Ca ions prevents or weakens the 

 poisonous effects of even large quantities of NaCl. 



I will now consider some possible objections to our theory. 

 One might think that with the CaCl 2 a small amount of HO 

 ions might possibly be introduced in cases in which the 

 CaCl 3 was heated before it was dissolved. One might think 

 that these HO ions were the essential constituent that 

 prolonged the life of these fish. The K ions were only 

 needed to overcome certain effects of the Ca ions. There is 

 indeed an antagonism between K and Ca ions, as shown by 

 Ringer's experiments. But the fact that Fundulus lives 

 indefinitely in distilled water proves that HO ions are not 

 necessary to maintain its life. The second objection might 

 be that NaCl used contained impurities. But this objection 

 may be discarded at once. The NaCl was obtained from 

 several leading factories and was chemically pure. The only 

 impurity possible could have been a trace of K. But as a 

 further addition of K made the NaCl more harmless, it is out 

 of the question that the trace of KC1 which the NaCl might 

 have contained could have had anything to do with the 

 poisonous effects. A third possible objection might be that 

 these experiments only prove the necessity of K and Ca ions 

 for Fundulus. But this idea is refuted by the fact that 

 Fundulus can live indefinitely in distilled water, it is, per- 

 haps, worthy of mention that the positive proof for the 



