132 



BOTANICAL GAZETTE 



[AUGUST 



TABLE II. 

 DURATION OF LIFE IN DAYS. GROUP 2. 



2. The pure solution of each of the salts added to inhibit the 

 poisonous effects of NaCl is itself poisonous at the concentration 

 at which it exists after its addition, since the plants die in such a solu- 

 tion much sooner than, in distilled water. 6 A mixture of solutions 

 which are individually poisonous produces a medium in which the 

 plants live indefinitely. 



That the plants die so quickly in solutions containing a single salt 

 might be attributed to the fact that the osmotic pressure of some 

 of these solutions is much lower than that of sea water. This sup- 

 position is disproved by the fact that in general the plants live longer 

 in tap water than in any solution containing but a single salt, although 

 the tap water has a lower osmotic pressure than that of any solu- 

 tion used in the experiments. (The plants of Group i live longer 

 in distilled water also. The tap water is to be regarded as a physi- 



6 This statement does not apply in all cases to CaCl 2 , which is the least toxic of 

 the salts employed and for some forms quite harmless in dilute solutions. 



