Role of Salts in Preservation of Life 179 



inhibit each other from diffusing into the cells, and this conclu- 

 sion is based among others upon the following experiment. 



By dividing a Spirogyra filament into several portions it was found 

 that it was plasmolyzed in .2 m CaCL and in .38 m XaCl, but neither 

 in .195 m CaCla nor in .375 m NaCl. On mixing 100 c.c. .375 m 

 XaCl with 10 c.c. . 195 m CaClo and placing other portions of the same 

 filament in it, prompt and very marked plasmolysis occurred. 



The explanation for this observation lies in the fact that in 

 the mixture of NaCl and CaCl, the two salts render their 

 diffusion into the cell mutually more difficult. After a longer 

 period of time the plasmolyzed cells can expand again in a 

 mixture of NaCl and CaCl,, but that occurs much later than if 

 they are in the pure NaCl solution. 



These experiments are the analogue of the observation on the 

 embryo of the eggs of Fundulus in which a pure solution of 

 ZnSO^ diffused rapidly through the membrane or micropyle, 

 while, if both salts were present, the diffusion was inhibited 

 or considerably retarded. 



While the observations of Osterhout show that Overton was 

 not justified in using the experiments on plasmolj^sis to prove 

 that the neutral salts cannot diffuse into the cells, yet they do 

 not prove that these salts diffuse into the cell under normal con- 

 ditions. In Osterhout 's experiments the cells are in strongly 

 h^T^ertonic solutions and it does not follow that such solutions 

 act like isotonic, perfectly balanced solutions. 



VI 



Wasteneys and I have recently sho^Mi that the toxic action 

 of acids upon Fundulus can be annihilated by salts. If we 

 add 0.5 c.c. n/10 butyTic acid to 100 c.c. of distilled water these 

 fish die in 2| hours or less. In solutions which contain 0.4 c.c. 

 or less acid they can live for a week or more. If we add, 

 however, . 5 c.c. of butyric acid to 100 c.c. of solutions of NaCl 

 of various concentration, we find that above a certain limit 



