74 



University of California Publications in Agricultural Sciences [Vol.3 



Magowan, who showed in her experiments that, in the ease of wheat, 

 CaCl 2 is the least toxic of the four salts. Here also we find that 

 yeast exhibits a peculiar physiological character which does not agree 

 with either of the above divisions, the animals or the plants. Perhaps 

 this may throw some light on the relation of yeast to these two groups. 



SEEIES IV— SODIUM CHLORIDE 



As NaCl is the most toxic of all the salts, only a few pairs of flasks 

 were taken, from .001M to .2M concentration, together with a pair 

 of blanks. The experiment was carried on in the same way as the 

 others. From table 4 and the curves in figure 4. it is evident that 

 NaCl is the most toxic to the yeast. Even the concentration of .01 M 

 NaCl did not stimulate the growth of yeast, as it did with the other 

 salts. The highest growth in this case was in .001 M, and beyond that 

 it was toxic. 



18 



16 



jc 14 



■S 12 



X 



r*i 



*B 10 



.2 8 



6 



4 



.001 .01 .1 .2 

 Concentration of salt 



Fig. 4. — The ordinates represent the number of yeast cells in millions and 

 the abscissae, the concentration of NaCl. The ordinate at represents the 

 number of yeast cells in blank cultures. 



