1 



1917] 



DENN Y—PERMEA BILI T Y 



391 



were obtained with sodium chloride solutions. From these data 

 the writer has not been able to formulate any mathematical relation 

 between differences in concentration on opposite sides of the 

 membrane and the rate of water movement through it. Another 



TABLE XIII 



Rate of water movement as related to differences in concentration of 



solutions on opposite sides of membrane 



Membrane 



Solution 



Osmotic pressure 



of external 



solution 



Osmotic pressure 



of internal 



solution 



1 

 Effective osmotic 



pressure 



Rate per hour 



First 



U 



Second 



a 



» • .• • . • 



Third 



Fourth 



u 



NaCl 



a 



a 



Sugar 



u 



a 



18.43 

 36.86 



13-82 



27.65 



, IO.30 



21.25 



IO.30 



21.25 



O 



18.43 

 O 



13.82 



O 



IO.30 



O 

 IO.30 



18.43 

 18.43 



13.82 



13.83 



10.30 



1095 

 10.30 



IO-95 



48.29 



35-94 

 41.07 



• 2396 



20.54 

 10.84 



29.09 

 I5-63 



Fall 



TABLE XIV 



RATE OF WATER MOVEMENT WHEN CONCENTRA- 

 TION OF INTERNAL SOLUTION WAS INCREASED 



Osmotic pres- 

 sure OF EXTER- 

 NAL SOLUTION 



46. IO. . 



a 



u 



a 

 u 

 u 

 a 



Osmotic pres- 

 sure of inter- 

 nal SOLUTION 





O 



4.61 



9. 22 



13.82 



18.43 



23 05 

 27.65 



Water (in mg.) passing through 

 membrane per hour 



First 



67.74 



Second 



49.54 



45-21 



45-49 



3943 



3939 



3299 



26.96 



2427 



22.92 



18.86 



12.13 



10. 11 



61.67 



set of readings was taken in which cane sugar solutions were used. 



XV 



between concentration and rate is complex. 



From 



& 



2T 



of the internal solution; (2) that equal osmotic differences do not 

 necessarily produce equal rates; and (3) that no mathematical 

 relation has been noted between the concentration on opposite 



