THE PERMEABILITY OF CELLS 539 



surface. Such a concentration would have no effect on the alkah 

 or vice versa. 



If the urea glycerine or salts change the condition of the plasma 

 membrane it is surprising how little effect this has on the proto- 

 plasmic streaming, which continues for many hours in solutions 

 of these substances. 



If leaves are selected from the same or neighboring whorls on 

 the same plant concordant results may be obtained. But dif- 

 ferent plants and young and old leaves exhibit the greatest varia- 

 tions in resistance to NaOH, as separate experiments will show. 

 The solutions were contained in tightly corked glass vials to 

 prevent absorption of CO2. Two to four leaves were tested in 

 each experiment. 



Experiment 1. A. to NaOH, | saturated with CHCI3 tap 

 water — decolorized in 13 minutes. 



B. TO NaOH in tap water — decolorized in 90 minutes. Rota- 

 tion ceases in leaves in this solution in < 15 minutes, but if re- 

 moved to tap water (after 15 minutes) begins again in 16-20 

 minutes. 



C. I saturated CHCI3 in tap water — Rotation ceases, but if 

 removed to tap water (after 15 minutes,) begins again in < 

 15 minutes. 



Oae-sixth saturated chloroform increases the permeability of 

 Elodea cells to urea. Leaves removed from solution C after 

 ten minutes plasmolyse much less readily than control leaves of 

 the same plant in f urea. 



Experiment 2. A. /o NaOH + 0.75 m C2H5OH in tap water 

 — decolorized in ten minutes. 



B. /o NaOH + 0.37 m C2H5OH in tap water— decolorized 

 in 19 minutes. 



C. TTT NaOH in tap water — decolorized in 19 minutes. 



D. 0.75 m C2H5OH in tap water — rotation momentarily ac- 

 celerated, then slowed and continued slow for > 1 hour. 



E. 0.37 m C2H5OH in tap water — rotation hardly affected, 

 slightly accelerated if anything. 



Experiment 3. A. /o NaOH + 0.075 m NaCl in distilled 

 water — decolorized in 4 minutes. 



