377] B. E. Invingston 179 
nary way. By one method the absorption rates were deter- 
mined as volumes, the plant being sealed into a bottle com- 
pletely filled with the nutrient solution and furnished with a 
burette for measuring the volume of water absorbed. Tem- 
perature changes were corrected for by means of readings 
taken from a similar arrangement of bottle and burette with- 
out any plant. By the other method arrangement was made 
by which the plant could be suspended from the balance arm, 
its roots in the culture solution, with the surface of the latter 
always at the same mark on the basal part of the stem when 
the balance was in equilibrium. Thus, the buoyancy tending 
to lift the plant was very nearly the same at all weighings. 
During this weighing the split cork otherwise closing the cul- 
ture jar was removed. Observations were obtained usually 
at hour intervals, from before daylight in the morning to late 
in the evening. The plants used were: Coleus blumei, Fago- 
pyrum esculentum (buckwheat) and Mimosa pudica (sensi- 
tive plant). The experiments were carried out in an experi- 
ment greenhouse, in the autumn and early winter. The 
nutrient solution employed was of the Shive 3-salt type, 
apparently physiologically balanced as to salt proportions, 
and its total osmotic concentration was about 1.75 atmos- 
pheres. The results of eight tests, at different times of the 
year, may be briefly stated as follows. 
(1) Sept. 20, clear sky. Buckwheat plant. Transpiration was 
greater than absorption for the period 8:50 a. m. to 1:50 p. m, 
incipient drying amounting to 0.63 g. Absorption was greater than 
transpiration for the period 1:50 to 5:50 p. m., the plant gaining in 
weight 0.15 g. Wilting began during hour ending 10:50 a. m., when 
incipient drying amounted to 0.27 g. Transpiration for this hour 
was 0.81 g. and absorption was 0.59g. Transpiration for last hour of 
incipient drying was 0.98 g. and absorption was 0.96 g. Five out of 
six leaves were permanently wilted and never recovered. 
(2) Sept. 21, clear sky. Buckwheat plant. Transpiration was 
greater than absorption for the period 9:20 a. m. to 1:20 p. m, 
incipient drying amounting to 0.24 g. Absorption was greater than 
transpiration for the period 1:20 to 9:20 p. m., the plant gaining 
in weight 0.38 g. Wilting began during hour ending 10:20 a. m., 
when incipient drying amounted to 0.08 g. For this hour transpira- 
