GENERAL PHYSICAL CONSTITUTION OF LIVING MATTER 49 



this purpose. In order to prevent the poisonous effect of a — - ZnSO^ 



solution, so much NaCl had to be added that the concentration of the 



NaCl in the solution was about -^. About 50 molecules of NaCl were 



therefore required to render one molecule of ZnS04 harmless. The fact 

 that the antitoxic effects of the salts with bivalent cations are so much 

 greater than those of the salts with univalent cations is possibly respon- 

 sible for the fact that I did not succeed in rendering a f m NaCl solution 

 harmless through the addition of a salt with a univalent cation. The 

 concentration of the solution would become so high that this might be 

 sufficient to kill the eggs. The salts of certain metals are especially 

 toxic, it being impossible to use those like Cu or Hg for antitoxic effects, 

 as they cause coagulation of the contents of the egg in smaller concen- 

 trations than are required for the antitoxic effects of such a solution. 

 The development of the egg of Fundulus requires at summer tem- 

 perature from about twelve to twenty-four days. If we use a Ca salt 



to render a — or f w NaCl solution harmless, an embryo can be formed, 



and it may hatch, but will then die ; if, however, a Zn or Ba salt be used 

 for this purpose, an embryo is formed, and it may develop for a number 

 of days quite normally ; but it dies before its development is complete. 

 If we allow the egg to complete its development in distilled water or 

 sea water, and put the larva, after it has hatched, into a mixture of 



100 c.c. — NaCl, and a small amount of a Ba, or Co, or Zn salt, the 

 2 



embryo dies even more quickly than if put into the pure NaCl solution. 

 These facts indicate that for this fish the ZnSO^ remains toxic even 

 in the presence of the NaCl, and that these two salts are only antago- 

 nistic as long as the fish is surrounded by the egg membrane. This sug- 

 gests the idea that the antagonism between these two salts is due only to 

 the fact that they retard each other's rapidity of diffusion into- the egg.* 



vyt 



If the egg is put immediately after fertilization into a — NaCl solution, 



very soon so much NaCl diffuses into the egg that it poisons the fish. 

 The same is true if a small amount of ZnSO^ is put into distilled water. 

 But if both salts are put together into the distilled water, neither the 

 NaCl nor the ZnSO^ can diffuse as rapidly into the egg, and the germ 

 lives long enough to form an embryo. In a few days, however, death 

 occurs, showing that the diffusion of the ZnSO^ was not prevented, 

 but only retarded. Another fact corroborates the idea that it is only 

 * Loeb, PflUger's Archiv, Vol.. 107, p. 252, 1905. 



