420 



RELATIVE TOXICITY OF HALIDES 



likely that the controlling factor is the relative penneability of the 

 cell membrane to these ions. The important factor is probably a 

 direct chemical action of the foreign ion on the cell protoplasm or some 

 part of it. 



Finckh has shown that very similar results are obtained with 

 iodide and nitrate-Ringer solutions. Our results are in agreement, 

 but it seems to us, on chemical grounds, since this parallel toxicity 



Per Cent 

 HaCl 100 

 100 



220 hours 



Fig. 2. Effect of substitution of chloride in Locke solutions by other anions 

 on the survival period of frog muscle. 



persists in solutions in which the I and NO3 concentrations are very 

 slight, that it is extremely unlikely that Finckh's conclusion is correct 

 that the toxicity can be traceable to the formation of elementary 

 iodine and of NO2 ions. 



Our results show (Fig. 2) a distinct difference of action in solutions 

 in which 2 and 3 per cent of chloride ion is replaced by iodide and 

 nitrate. For the greater replacement iodide is more toxic than nitrate ; 



