208 
Smith and Butler. — Relation of 
solution than those growing in the full nutritive solution; and the plants 
growing partly in the absence of potassium were subjected to a change of 
concentration upon its addition from 2-4815 grm. per litre to 3*6635 grm. It 
seemed to us necessary to verify the fact that growing plants in the weaker 
concentration did not affect them adversely, and so in one experiment with 
wheat the concentration of the less potassium solution was increased to that 
of the full nutritive solution by the addition of calcium sulphate and 
magnesium sulphate in the ratio 3-85 : 1. The results obtained are indicated 
in Table XX, and show conclusively that the reduction in concentration 
used did not affect the growth of the plants. For convenience in working, 
a standard solution of potassium sulphate was made up, so that 25 c.c. con- 
tained the amount required per jar. In order to allow the addition of 
these 25 c.c., a like amount of nutritive solution was previously withdrawn 
T ABLE XX. Effect of concentration of nutritive solution on growth of Bine 
stem Wheat plants in the absence of potassium . 
Ratio of 
tops to 
roots. 
3-73 
1 
Concentration per 
A r o of 
Total weight of plants. 
Dry weight of 
litre. 
plants . 
Green. Dry. 
Tops. Roots. 
Grm. 
Grm. Grm. 
Grm. Grm. | 
3-6635 
5 
0.6570 0.140 1 
0.1120 0-0281 
0.5803 0.125 1 
0-0969 0.0282 
Mean 
1 
0.1237 0.0265 
0.0209 0.0056 
2.4815 
Mean 
0-6461 
0.6393 
0.1378 
0.1213 
0-1086 
0.0962 
0-1285 0-0259 ! °-° 20 ' 
0-0292 ; 
0.0251 j 
0.0054 I 
3-79 
and placed in small stoppered flasks until it could be returned. After the 
potassium had been added the jars were aerated to ensure thorough 
mixing. 
Experiment r. In this experiment Blue stem Wheat* was used, and the 
plants were grown in solutions A and F, the latter both as a full nutritive 
solution and modified as required for the purpose of studying the effect 
of delayed additions of potassium. Three days after the seed had been 
placed in the germinator the seedlings had grown sufficiently to be trans- 
ferred to the nutritive solutions. Five plants were grown in each jar, and 
there were two jars of plants in solutions A, F, and F less potassium, but 
four jars in each case for the study of the effect of delayed additions of 
potassium. 
The experiment was set up on February 1 1 and allowed to run twenty- 
one days. At the close of the experiment the plants in the full nutritive 
solutions were healthy and growing vigorously, and had stooled ; their root 
