Toxic AND ANTITOXIC EFFECTS OF IONS 713 



stages of segmentation, but dies when it reaches the thirty- 

 two- or sixty-four cell stage. The concentration of a |-m 

 sodium-chloride solution is indeed so high above the point 

 of the fatal concentration of sodium chloride that a slight 

 decrease in the degree of dissociation of the NaCl solution 

 brought about through the addition of a small amount of 

 another salt having a common ion, could be entirely dis- 

 regarded. In the following experiments, however, salts with 

 different ions were combined, wherever this was possible. 



If to a pure sodium-chloride solution a trace of a 

 calcium salt is added, as many eggs develop as in ordi- 

 nary sea-water, as shown by Table I. 



TABLE I 



This series of experiments does not show whether it is 

 the Ca or the SO 4 ion that has the antitoxic effect. To 

 determine this point the same series of experiments was 

 twice repeated with certain modifications. In the first of 

 these Ca(NO 3 ) 2 was added to the | NaCl solution instead of 

 CaSO 4 . The result was practically that given in Table I. 

 In the second Na 2 SO 4 was added to the sodium -chloride 

 solution. The addition of Na 2 SO 4 did not inhibit the toxic 

 action of the sodium chloride, and the eggs developed no better 

 than in the pure sodium-chloride solution. We shall return 

 to this point later. However, in order to eliminate entirely 

 the effect of the anions in the antitoxic effects produced, a 



