1917] 



DENN Y—PERMEA BILI T I 



379 



precautions 



membranes 



water before being used for experimental purposes. The distilled 

 water used inside the osmometer was previously boiled to drive 



off dissolved gases. 



made to determine that no leakage 

 In filling the osmometer care 



was occurring in the apparatus, 

 was taken to drive out all air bubbles from the internal portion 

 of the apparatus. Special pains were taken to see that no air 

 bubbles were lodged on the membrane. 



Effect of temperature 



Membranes of the seed of Arachis hypogaea 



measurement 



of water at the temperatures 

 at the various temperatures, 



After being measured 





1 

 2 



3 

 4 



5 

 6 



7 

 8 



9 

 10 



11 



12 



TABLE II 



Effect of temperature upon permeability of seed coat (membram 



of Arachis hypogaea) 



Number 



Osmotic ' ^ ater (* n m &-) passing through 19. 635 sq. mm. of membrane per hour 



pressure at 

 25°C. 



2765 



a 

 a 



41.48 



a 



5.2C 



II .OI 

 22.93 



15.2 c 



25.2 c 



35. oC 



45. oC 



18.59 

 38.08 



u 

 u 



13.82 



16.51 



33 02 

 42.19 



37-91 



a 

 u 

 u 





13-45 

 15-41 



28.32 



53 12 

 69.07 



59 03 



21 



2 S 





24 79 



From left to right, the figures are readings obtained from the same individual membrane at different 

 temperatures; each line represents a different membrane. 



against a previous temperature to be certain of constant behavior. 

 In transferring from one temperature to another the membrane 

 was not removed from the osmometer, so that the results indicated 

 in table II show a comparison of the rates indicated by the same 

 membrane at different temperatures. When the bathing solution 



m 



also changed, and a correction was made for this change in osmotic 



