538 
Journal of Agricultural Research 
Vol, VII, No. 12 
to 6, and this plan was maintained throughout the experiment, so that 
the time periods for each plant between any two weighings were approxi¬ 
mately the same. At the end of the standardization period the plants 
of series A were sprayed. This series now became series A'. The 
Bordeaux mixture employed was prepared according to the same formula 
as that used in the experiments with abscised leaves. The spray was 
applied to the leaves of the plants with an atomizer. This method gives 
a very uniform film of the spray over the leaf surfaces. The spray was 
applied to both the upper and lower surfaces of the leaves, except in the 
experiments with cabbage plants. 
At the close of an experiment the tops were severed from the roots 
just at the surface of the wax seal, and the green weights were imme¬ 
diately obtained. The plants were then placed in weighing bottles and 
dried in an oven at a temperature of from 76° to ioo° C. for a period of 
28 hours, after which they were dried to constant weight at a temperature 
of from 102 0 to 105° C. The bottles were then transferred to a large 
desiccator and were allowed to cool to room temperature before weighing. 
Measurements were taken of the evaporating power of the air in the 
greenhouse room where the experiments were carried out. These measure¬ 
ments were made by means of standardized porous-cup atmometers (13); 
the instruments were placed among the plants on the greenhouse bench 
and readings were taken each day at the time when the plants were 
weighed. The readings were corrected to the Livingston cylindrical 
standard by multiplying by the coefficient of correction of the cup used. 
In the time during which the experiments were conducted the water 
loss from the porous-cup atmometer gave a daily mean of 10.4 c. c.; a 
maximum daily rate of 24.0 c. c. (on March 1) and a minimum daily 
rate of 6.0 c. c. (on March 6). 
As in the experiments with abscised leaves, one of the two groups of 
plants comprised in a single experiment will be designated “series A.** 
The other group, remaining untreated throughout the experiment, will 
be designated “series B.” In the experiments with potted plants, 
transpiration quantities for series A and for series B will be denoted 
“A” and “B” in their respective series. This method of notation is 
precisely the same as that adopted in the experiments with abscised 
leaves. 
In presenting the data for the experiments with potted plants the 
ratios between the water loss per gram of green substance for periods 
before and after spraying, as well as the corresponding water loss per 
gram of dry substance, will also be treated. Green- and dry-weight 
values could, of course, not be obtained until the close of an experiment. 
These values must serve, therefore, for the calculation of ratios for the 
standardization periods as well as for the periods after spraying. This, 
however, could make no material difference in the ratio values for periods 
before spraying, since any increase in the weight of plant substance due 
