1917] DENNY— PERMEABILITY 395 



* 



Brown and Worley with non-living seed coat membranes, (4) 

 Pfeffer with copper ferrocyanide membrane. 



7. No hysteresis or after effect of a previous temperature was 

 observed. 



8. It was found that the seed coats of peanut and almond 

 showed a difference in permeability to water in opposite directions 

 through the membrane, the faster rate being from the external 

 toward the internal portion of the seed. 



9. When distilled water was placed on one side of the membrane, 

 the rate of water movement was proportional to the osmotic 

 pressure applied upon the other side, when sodium chloride solutions 

 were used; but this proportionality did not exist when cane sugar 

 solutions were used. 



10. When solutions of varying concentrations were placed on 

 opposite sides of the membrane, it was found that the relation 

 between rate and concentration difference was complex, and that 

 in general equal osmotic differences do not necessarily produce 

 equal rates; the rate is greatly affected by changes in the con- 

 centration of the internal solution; no mathematical relation was 

 noted between the concentration on opposite sides and the rate 



through the membrane. The bearing of these 



movement 



facts upon plasmolytic experiments based on rate of water move- 



membran 



11. A comparison of the permeability of several plant mem- 

 branes under similar conditions was made, large differences 

 appearing. 



William 



Crocker for suggesting the problem and rendering valuable 

 assistance during the course of the experiments. 



142 South Anderson Street 



Los Angeles, Cal. 



LITERATURE CITED 



1. Armstrong, Henry E., Hydrolysis, hydrolation, and hydronation as the 

 determinants of the properties of aqueous solutions. Proc. Roy. Soc. 

 London A. 81:80-95. 1908. 

 Barber, Kate G., Comparative histology of fruit and seeds of certain 



species of Cucurbitaceae. Bot. Gaz. 47: 263-31°- 



009 



