377] B. E. Livingston 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 arid 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 gaming 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 0.59 g. 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- 



