1918] 
DUGGAR AND BONNS—RATE OF TRANSPIRATION 157 
very careful attention was given to watering. This was done 
at intervals sufficiently frequent and in such quantity as to 
maintain a fairly constant water relation. In the case of all 
potted plants, where the load was considerable, weighings 
were made to within 1 gram on a Troemner balance. More- 
over, in carrying out the weighings the observer used the 
same sequence, beginning always with plant No. 1 and con- 
cluding the 8 weighings in 6-8 minutes. Therefore, the ob- 
servation intervals varied by a maximum of less than 2 
minutes for the plants in any series, so that with intervals 
generally greater than 1 hour such variations are entirely 
negligible. 
As in our earlier work, and as followed by subsequent in- 
vestigators, observations were made on the basis of several 
to many standardization intervals prior to spraying; that is, 
the rates of the plants to be sprayed and of those to remain 
as the control were first determined, furnishing a basis for 
a ratio between controls and those to be Bordeauxed. Then 
after the applieation of the sprays to the plants designated 
for these—allowing sufficient time for the complete drying of 
the films—observations were again made on the control and 
the sprayed plants for a suitable number of intervals. 
EXPERIMENTAL 
The experimental data are included in a series of tables 
arranged in a manner as uniform as possible. In the first 
column at the left of each table is recorded a number by 
means of which to identify the various time intervals, or 
**runs?'; in the second column the actual period of time cov- 
ered by the interval is included (likewise ratios computed 
from the remaining columns), and then follow 8 columns— 
for the 8 plants involved in each experiment—numbered in 
order and giving the transpiration quantities for each. The 
letters accompanying the numbers signify the treatment pro- 
posed or given; thus, during any standardization interval 
K = control, B = Bordeaux, BL = Bordeaux with excess of 
lime, L — a lime wash, and BC — Bordeaux with exeess of 
the copper salt. Other letters will be explained in connection 
