186 The Mechanistic Conception of Life 



If we try to render NaCl harmless by KCl and CaClg we 

 find that CaCl^ can antagonize even a 6/8 m and a 7/8 m solu- 

 tion of NaCl, while KCl ceases to show any antagonistic effect 

 if the NaCl solution exceeds m/2 or 5/8 m. 



Experiments with pure CaCl, solutions give the result that 

 this substance is harmless 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 CaCla in 100 c.c. 

 Botanists have also found that weak solutions of CaClg are 

 comparatively little toxic. This gives us the impression that 

 the effect upon the surface film of protoplasm produced by 

 CaClg is especially important 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 

 deprived 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 con- 

 centration of the NaCl in the sea-water and in the blood that, 

 in addition to KCl and NaCl, CaCl, is needed. But the case 

 is not so unequivocal as the previously mentioned cases of 

 antagonism between only two electrolytes. 



VIII 



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 an opportunity is offered us through the- 



