488 Trans. Acad. Sci. of St. Louis. 



directly inhibitory to starch formation. Sodium chloride in 

 in tap-water, at a concentration of 7.5 per cent was not re- 

 ported as particularly injurious to this species. Since in all 

 of my experiments, sodium chloride is nearly or quite as 

 toxic as the nitrates, it might be inferred that the threshold 

 of toxic action may not be modified on account of any special 

 stimulating effect which this salt may have upon any partic- 

 ular function, even though this stimulating effect may be 

 manifested at a concentration approaching the lethal dose. 



Parallel with my experiments already reported, tests were 

 made in which .35, .30, .25 N, cane sugar, was used in sea 

 water. In such solutions there was no indication of injury 

 throughout the period of the experiments. At a higher tem- 

 perature there is injury in a few days, doubtless due to bac- 

 terial action. At the same time, a concentrated sea water 

 was prepared by evaporation. The strength of this varied 

 from one and one-half to double strength. In such solutions 

 there was no injury, neither throughout the period of the ex- 

 periments proper, nor for a week or two afterwards. In fact, 

 the algae seemed to be iu excellent condition as lonjr as the 

 solutions were kept. A solution stronger than double strength 

 sea water was not employed, unfortunately, although it is 

 quite possible that at a strength greater than this some crystal- 

 lization would result in the low temperature at which the ex- 

 periments were conducted. In the double strength sea water 

 it is evident that the concentration of sodium chloride is 

 greater than in the solution which caused injury when sodium 

 chloride alone was added to sea water. This was particularly 

 true with reference to Grinuellia and Ceraniium, for these 

 algae (each in its series) were somewhat more sensitive to 

 sodium chloride than the other species employed. It is 

 therefore probable that the concentration of the other salts in 

 the double strength sea water acted as an antidote (Loew), 

 or antitoxic (Loeb) agent, for the excess of sodium chloride. 

 Such relationships of solutes, or the mollification of toxic 

 action in mixed solutions requires much further study. 

 Special attention seems to have been called to this matter in 



