







1917] 



DEXX V—PERME. 1 BIUTY 



38 



"J 



Brown and Worley (6) determined the speed of intake of 

 water by barley grains immersed in water at different temperatures. 



Their results gave a temperature coefficient of 1.8 



1.9 



Since 



this approached closely the van't Hoff coefficient (2-3) for the 

 effect of temperature on the rate of chemical reaction, they con- 

 sidered that chemical processes were involved in the penetration 

 of water through the semipermeable membrane of the barley grain. 

 This chemical reaction, according to their view, took place in the 

 water itself, that the effect of temperature was to split the larger 

 aggregates of water into simpler ones, and that only these simpler 

 molecules were transmitted by the differential septum. This was 

 offered as evidence in favor of the hydrone conception of 

 Armstrong (i) as to the composition of water. 



Pfeffer (24) measured the rate of water movement across the 

 copper ferrocyanide membrane at different temperatures with the 

 following results: 



Temperature 







In stream per hour 



7?i 







5.9 mm. 



I7?6 







9 4 " 



32?5 







13-3 " 



; give values of Q I0 



as follows: 



J.i- 



-17-6, 



Qio 



= 1558 



17.6- 



-32-S, 



Qio 



= 1 .266 



The writer's observed values are in fair agreement with these 

 figures. For purposes of comparison, a summary is given in table 



VI. 



will be noted from 



TABLE VI 





Observer 



Krabbe 



Rysselberghe 



Brown and Worley 



Pfeffer 



The writer. . . . 



Nature of membrane studied 



Living pith cells of 

 H el i ant has 



Living cells 



Semipermeable mem- 

 brane of barley seed 



Copper ferrocyanide . . . 



Seed coat of Arachis 

 hypogaea 



Temperature range 



0-4 to 20-26 

 O to 30° 



3.8 to 34-6 

 7 1 to 32?5 



3-6 to 45° 



Q 



1© 



2.0 to 2.5 

 2.0 



1.9 to 1.8 

 1.558 to 1.266 



1.641 to 1.343 



observed. 



membrane 



peanut 



