NOVEMBEE 17, 1911] 



UCIENGE 



657 



ease, namely, that NaCl is required to 

 render the solutions of many of the bi- 

 valent metals, for instance ZnS04, harm- 

 less. (That the SO4 ion has nothing to do 

 with the result was shown before by experi- 

 ments with NajSO^.) 



If the eggs of Fimdulus are put imme- 

 diately after fertilization into distilled 

 water, a large percentage of the eggs de- 

 velop, often as many as one hundred per 

 cent., and the larvse and embryos formed 

 in the distilled water are able to hatch. 

 If we add, however, to 100 c.c. of distilled 

 water that quantity of ZnS04 which is re- 

 quired to render the NaCl solution harm- 

 less, all the eggs are killed rapidly and not 

 a single one is able to form an embryo. 

 If we add varying amounts of NaCl we find 

 that, beginning with a certain concentration 

 of NaCl, this salt inhibits the toxic effects 

 of ZnSO^ and many eggs are able to form 

 an embryo. This can be illustrated by the 

 following table. 



Percentage of 

 the Eggs Form- 

 ing an Embryo 

 49 



Nature of the Solution 



100 C.C. distilled water 



100 c.c. distilled water 



-j-S c.c. m./32 ZnSO, 



100 c.c. m./64 NaCl-l-8 c.c. m./32 ZnSO, 



100 c.c. in./32 NaCl -1-8 c.c. m./32 ZnSOi 3 



100 c.c. m./16 NaCl+8 c.c. m./32 ZnSO. 8 



100 c.c. m./8 NaCl-l-8 c.c. m./32 ZnSO. 44 



lOOc.c. m./4 NaCl-l-8 c.c. m./32 ZnSOj 38 



100 e.c. 3/8 NaCl-l-8 c.c. m./32 ZnSO. 37 



lOOc.c. m./2 NaCl-l-8c.c. m./32ZiiSOi 34 



100 c.c. 5/8 NaCl-l-8 c.c. m./32 ZnSOj 29 



100 e.e. 6/8 NaCl-f8 c.c. iu./32 ZnSOi 8 



100 CO. 7/8 NaC14-8 CO. m./32 ZnSO. 6 



lOOc.c. m. NaCl-(-8 c.c. m./32 ZnSO. 1 



This table shows that the addition of 

 NaCl, if its concentration exceeds a certain 

 limit, namely, m./8, is able to render the 

 ZnSOj in the solution comparatively harm- 

 less. 



If we now assume that ZnSO^ renders 

 the 5/8 m. NaCl solution harmless by ren- 



dering the egg membrane comparatively 

 impermeable for NaCl we must also draw 

 the opposite conclusion, namely, that NaCl 

 renders the egg membrane comparatively 

 impermeable for ZnS04. We, therefore, 

 arrive at a new conception of the mutual 

 antagonism of two salts, namely, that this 

 antagonism depends, in this case at least, 

 upon a common, cooperative action of both 

 salts on the egg membrane, by which action 

 this membrane becomes completely or com- 

 paratively impermeable for both salts. 

 And from this we must draw the further 

 conclusion that the fact that each of these 

 salts, if it is alone in the solution, is toxic, 

 is due to its comparatively rapid diffusion 

 through the membrane, so that it comes 

 into direct contact with the protoplasm of 

 the germ. 



As long as we assumed that each of the 

 two antagonistic salts acted, if applied 

 singly, in the opposite way from its antag- 

 onist, it was impossible to understand these 

 experiments or find an analogue for them 

 in colloid chemistry. But if we realize 

 that NaCl alone is toxic because it is not 

 able to render the egg membrane imper- 

 meable ; and that ZnSO^ if alone in solution 

 is toxic for the same reason ; while both 

 combined are harmless (since for the "tan- 

 ning" of the membrane the action of the 

 two salts is required) these experiments 

 become clear. 



We may, for the sake of completeness, 

 still mention that salts alone have such 

 antagonistic effects; glycerine, urea and 

 alcohol have no such action. On the other 

 hand, ZnS04 was not only able to render 

 NaCl harmless, but also LiCl, NH4CI, CaCl, 

 and others; and vice versa. 



These experiments on the egg of Ftin- 

 dulus are theoretically of importance, since 

 they leave no doubt that in this case at 

 least the "antagonistic" action of salts con- 

 sists in a modification of the egg membrane 



