662 



SCIENCE 



[N. S. Vol. XXXIV. No. 881 



The coefficients are not as regular as in 

 the ease of antagonization of KCl by NaCl. 

 This is due to the fact that the minimal 

 value of CaCl, at which it renders the KCl 

 harmless can not be determined as sharply 

 as the limit for NaCl. "Why is less CaCl2 

 required than NaCl ? "We can only answer 

 with a suggestion first offered by T. B. 

 Robertson, namely, that CaCL produces its 

 protective effect through the formation of 

 a comparatively insoluble compound (in 

 this case on the gills or the rest of the sur- 

 face of the animal) while NaCl acts 

 through the formation of a compound 

 which is more soluble. This view is cor- 

 roborated by the observation which we 

 made, that Sr is just as effective to antagon- 

 ize KCl as CaCl,, but that Mg is much less 

 efficient. This would correspond with the 

 well-known fact that many strontium salts 

 are just as insoluble, if not more insoluble, 

 than the calcium salts, while the magne- 

 sium salts are often incomparably more 

 soluble, for instance in the case of the sul- 

 phates. BaCL antagonizes KCl also pow- 

 erfully, but, probably, in consequence of 

 the fact that the substances formed at the 

 surface of the animal or the gills, diffuse 

 slowly into the cells, the fish do not remain 

 alive as long if Ba is used as if the more 

 harmless Ca and Sr are used. 



It is very remarkable that CaClj renders 

 harmless any given concentration of KCl 

 below 6.6 c.c. m./2 KCl in 100 c.c. of the 

 solution, but not above this limit. This 

 limit is exactly the same which we found in 

 the ease of antagonization of KCl by NaCl. 

 Even the combination of NaCl and CaClj 

 does not permit us to render harmless more 

 than 6.6 e.e. m./2 KCl in 100 c.c. of the 

 solution. 



If we try to render NaCl harmless by 

 KCl and CaCU we find that CaCl, can 

 antagonize even a 6/8 m. and a 7/8 m. so- 



lution of NaCl, while KCl ceases to show 

 any antagonistic effect if the NaCl solution 

 exceeds m./2 or 5/8 m. 



Experiments with pure CaClj solutions 

 give the result that this substance is harm- 

 less in a solution of that concentration in 

 which this salt is contained in the sea- 

 water. Fundulus can live indefinitely in 

 a solution of 1.5 c.c. m./2 CaCl, in 100 c.c. 

 Botanists have also found that weak solu- 

 tions of CaClg are comparatively little 

 toxic. This gives us the impression that 

 the effect upon the surface film of proto- 

 plasm produced by CaClg is especially im- 

 portant for the protection of the proto- 

 plasm. This conclusion receives an indirect 

 support by the well-known experiments of 

 Herbst, who found that in sea-water de- 

 prived of calcium the segmentation cells of 

 a sea-urchin embryo fall apart through the 

 disintegration or liquefaction of a film 

 which surrounds the embryo and keeps the 

 cells together. If such eggs are brought 

 back into solution containing calcium the 

 film is restored and the cells come into close 

 contact again. 



It is therefore not impossible that the 

 mechanism of the antagonism between KCl 

 and NaCl is similar to that found between 

 NaCl and ZnSo^. It seems only due to the 

 high concentration of the NaCl in the sea- 

 water and in the blood that, in addition to 

 KCl and NaCl, CaCla is needed. But the 

 case is not so unequivocal as the previously 

 mentioned cases of antagonism between 

 only two electrolytes. 



It is necessary for our understanding of 

 the life-preserving action of salts that we 

 do not depend merely on conclusions drawn 

 from experiments, but that we must be able 

 to see directly in which way abnormal salt 

 solutions cause the death of the cell. Such 



