1911.] 



The Permeability of the Yeast-Cell. 



297 



within the cells to be available for mixture with alcohol, the concentrations 

 of alcohol inside and outside the cells, after osmotic equilibrium had been 

 established, would be equal. 



Now the grammes of substance (in this case alcohol) per 100 grm. of 

 water within the yeast (P), divided by the grammes of substance per 

 100 grm. of water outside the cells (Pi), gives a measure (K) of the amount 

 of diffusion which has taken place. In the case under discussion, therefore, 

 K would be expected to be equal to unity. 



In these experiments the increase of alcohol due to auto-fermentation 

 could not be neglected. The total amount of alcohol present at the end of 

 the experiment was therefore determined by analysis of the liquid poured 

 off and of the residue after centrifuging. The weight of alcohol due to 

 auto-fermentation was thus found by difference from the original amount, 

 and was embodied in the calculation for the weight of liquid outside the 

 cells. The formation of an amount of alcohol (F) during an experiment 

 occasions a loss of an approximately equal amount of carbon dioxide to be. 



Table V. — Diffusion of Alcohol of varying Concentrations. 





Conditions. 





Yeast. 



Liquid. 





Pi. 





No, 





Initial. 



Final. 



Initial. 



Final. 



1 



P. 





75 



Alcohol, 2 -5 molar, 

 stood 3 hrs. at 

 room temperature 



Total ... 

 Alcohol 



100 -oo 



4-29 



95 -70 

 5-80 



98 -00 

 11 -47 



101 -90 

 10 -78 



9-91 



12 -08 



0-82 | 



76 





Total ... 

 Alcohol 



100 -oo 

 4-50 



95 -50 

 5-60 



98-00 

 11 -47 



102 -30 

 10-42 



9 13 



10 -95 



0-83 



77 



Alcohol, 2 "5 molar, 

 stood 20 hrs. in 



Total ... 

 Alcohol 



100 -oo 

 3-14 



98 -17 

 5-50 



98 -00 

 11 -47 



99 -57 

 9-50 



8-97 



10 -65 



0-84 



80 





Total ... 

 Alcohol 



100-00 

 3-48 



91 -08 



5 36 



98 -00 

 11 -47 



106 -16 

 10 -62 



9-62 



11 -30 



0-85 



100 



Alcohol, 1 '3 molar, 

 stood 20 hrs. in 

 cold room 



Total ... 

 Alcohol 



100-00 

 3-39 



97 -56 

 3-42 



98 -80 

 6-00 



100-47 

 6-63 



5-31 



7-13 



0-74 



101 





Total ... 

 Alcohol 



100 -oo 

 3-47 



94-01 

 3-55 



98 -80 

 6-00 



104 -31 

 6-84 



5-95 



7-07 



0-84 



81 



Water, stood 20 hrs. 

 in cold room 



Total ... 

 Alcohol 



50 -00 



47-07 

 0-64 



100 -oo 



102 -59 

 2-11 



1-96 



2-11 



0-92 



85 



n 



Total ... 

 Alcohol 



100 -oo 



4-44 



94 -16 

 1 -37 



100 -oo 



105 -48 

 3-42 



2-16 



3-38 



0-64 j 



90 





Total ... 

 Alcohol 



100 -oo 

 4-65 



99-83 

 1-86 



100-00 



99 -90 

 3 -19 



2-66 



3-34 J 



0-79 | 



z 2 



