680 



SCIENCE 



[N. S. Vol. XXXVI. No. 933 



The deleterious effect of a l.Y per cent. NaCl 

 solution to which .09 per cent. CaSO, had been 

 added proved, as one might expect, greater 



K and Na. For Mg this is certainly true, al- 

 though its antagonism to Na is much less 

 marked, as the results given below show. 



Time of acclimatization 34 hours. 



Average strength of preparatory solution in Na .248 per cent. 



Average strength of preparatory solution in Ca .013 per cent. 



than that of the pure NaCl solution. Even 

 when diluted one half 93 per cent, of the 

 larva died in 13 hours. However, preliminary 

 treatment with more dilute solutions, even for 

 a relatively short time, not only practically 

 doubled the time during which the larvse can 

 endure the .85 per cent, solution, but only 7 

 per cent, died in 24 hours. In tabular form: 



Comparison with the results with pure 

 NaCl shows that the presence of the Mg en- 

 ables the larva to withstand a solution of in- 

 creasing concentration with average strength 

 of .199 per cent. !NaCl for 104 hours without 

 a single death, whereas in the absence of Mg, 

 33 per cent, die in 101 hours. Both in the 

 presence and absence of Mg, however, there 



Time of acclimatization 104 hours. 



Average strength of preparatory solution in Na .199 per cent. 



Average strength of preparatory solution in Mg .0199 per cent. 



Comparing this result with the first accli- 

 matization, it is seen that when Na and Ca 

 are present roughly in the proportion of 50 to 

 1, the tadpoles may be acclimated to the 

 .85 per cent, solution about three times as 

 fast as in the absence of the Ca, and further- 

 more that 93 per cent, of the larvse so treated 

 can endure this solution for 24 hours, whereas, 

 in the absence of Ca, none survive. Al- 

 though the concentrations here dealt with are 

 lower than those reported by Pearse, although 

 not much lower than his weakest solution, the 

 proportion of Na to Ca is, according to Forch- 

 heimer, identical. 



Other Antagonisms. — In a series of investi- 

 gations Loeb and Wasteneys° have demon- 

 strated and measured the antagonistic effects 

 of KCl and NaCl on Funduhis, so that in view 

 of the fact that the findings with reference to 

 Ca can be verified on the frog larva, it seems 

 reasonable to assume similar relations for the 



' Biochemische Zeitschrift, Bd. 31 and 32. 



were no survivors in the .85 per cent, solution 

 after 24 hours, which shows that the Na-Mg 

 antagonism is less pronounced than that be- 

 tween Na and Ca. 



While these experiments give some insight 

 into the conditions of survival for frog larvae 

 in sea water, the actual circumstances are 

 probably not as simple as one might at first 

 conclude, for granted an antagonistic action 

 between Na and K, Na and Ca, and Na and 

 Mg, it does not follow that in a solution in 

 which all these salts are present, the total 

 antagonistic effect toward Na could be repre- 

 sented by the formula, Na vs. (K -f- Ca + Mg) 

 for ions capable of antagonizing the Na may 

 antagonize each other. The existence of these 

 " accessory " antagonisms has been demon- 

 strated by Loeb and Wasteneys for Fundulus. 

 In the case of the frog embryos I found an 

 antagonistic action between Mg and Ca, for 

 although both these ions antagonize the Na, 

 yet a solution containing all three is a less 



