340 ROBERT AARON STEINBERG 
8. The effect of a decrease in concentration of one or more of the salts of the Pfeffer solution. 
lo : 5 : 2.5* 
10 :5 : 1 
10 : 2 : 2.5 
10 : 2 : 1 
t 0.Q17 s. 
^•ojO &• 
0 2Q7 P" 
0.2Q4. 
0.31 1 
0.276 
0.^Q7 
0.244 
0 'lOT 
0,261 
0.367 
0.271 
0.300 
0.342 
0.415 
0.304 
0.321 
0.300 
0.365 
0.284 
0.299 
4 : 5 : 2.5 
4:5:1 
4 : 2 : 2.5 
4:2:1 
0.254 g. 
0.238 g. 
0.284 g. 
t 0.796 g. 
0.207 
0.280 
0.164 
0.179 
0.254 
0.229 
0.162 
0.176 
0.223 
0.243 
0.163 
0.187 
0.152 
0.336 
0.178 
0.189 
0.218 
0.265 
0.190 
0.183 
* MgS04.7H20 (Kahlbaum). 
t Accidental zinc culture. 
All fruited in two days. 
9. The effect of a decrease in concentration of the monopotassium phosphate. 
4:2: o.oi| 
4 : 0.4 : o.oi 
4 : 0.08 : 0.01 
4 : 0.016 : o.oT 
0.128 g. 
0.104 g. 
O.IIOg. 
0.097 g. 
0.085 
0.I2I 
0.158 
0.078 
0.106 
0.138 
O.II7 
0.082 
0.245 
0.089 
0.137 
0.077 
0.107 
0.108 
O.II9 
0.088 
0.134 
O.II2 
0.128 
0.084 
X MgS04.7H20 (Kahlbaum). 
In these experiments we note that only a decrease in the yield follows a 
decrease in concentration of one or more of the inorganic constituents of 
the Pfeffer solution, and we may conclude therefore that none of them are 
present in toxic or in greater than optimum concentration. 
The effects of increasing the concentration of the electrolytes of the 
Pfeffer nutrient solution as well as of a decrease are shown in experiments 
10-16 inclusive. 
10. The effect of a variation in concentration of the monopotassium phosphate in the 
Pfeffer solution. 
10 : 25 : 2.5 § 
10 : 10 : 2.5 
10:0.1: 5 
10 : 0.01 : 2.5 
0.496 g. 
0.335 g. 
0.196 g. 
0.048 g. 
0.389 
0.327 
0.182 
6.048 
0.349 
0.355 
0.136 
0.053 
0.459 
0.334 
0.159 
0.058 
0.556 
0.266 ' 
0.169 
0.065 
0.450 
0.323 
0.168 
0.054 
§ MgS04.7H20 (Kahlbaum). 
