29 b: 



Mr. S. G. Paine. 



[July 12, 



subtracted from the total weight (W), and a loss of approximately twice the 

 amount of solid matter (2F) to he subtracted from V, since the alcohol is 

 formed according to the equation 



C 6 H 12 6 = 2C0 2 + 2C 2 H 5 OH. 



If F = weight of alcohol by auto-fermentation, W— F = the total weight 

 at the end of the experiment, and V — 2F = the weight of solid matter 

 finally present, and the formula given on p. 296 becomes 



j _ E(W-F)-100 (V-2F) = EW-100V-F(E-200) 

 E-G E— Gl- 



and Y is obtained by difference from W— F. 



The table shows very clearly that alcohol penetrates freely through the 

 cytoplasm of yeast,, but the interesting fact is observed that when 

 equilibrium is established the ratio of alcohol to water is, in every case, less 

 within the cell (P) than it is outside (Pi), and that these ratios stand to one 

 another in a fairly constant proportion (K). 



This points to the possibility that some of the water of the protoplasm 

 is bound up in such a manner as to render it unavailable as a solvent for 

 alcohol. This view is supported by the high value for K found in Experi- 

 ment 81, wherein old yeast was employed which contained a very large 

 vacuolar space and a correspondingly decreased layer of cytoplasm. 



The method is specially interesting, as it affords a very clear insight into 

 the interchange of material occurring between the cells and the surrounding 

 liquid. For instance, in Experiment 81 (yeast in water), - 36 grm. of 

 alcohol have been formed by auto-fermentation within the yeast, bringing 

 the total alcohol up to 2 - 75 grm. Of this 2*11 grm. have passed out into 

 the surrounding water, leaving 0'64 grm. in the final yeast ; 070 grm. of 

 solid matter have passed out from the yeast, and - 73 grm. of solids 

 have been fermented. At the same time there has been an entrance of 

 - 21 grm. of water into the cells, which is also accounted for as having left 

 the liquid. 



Since in these experiments the value of K appeared to be independent 

 of the concentration of the alcohol, it seemed advisable to investigate this 

 further, and also to try the effect of variations in other directions. Since 

 the factor K depends solely upon the analyses of the components of the 

 final system, in each of the experiments about to be described only two 

 estimations of total solids and two of alcohol were necessary. 



The results of these experiments are contained in the following Table VI. 

 In all cases, except where otherwise stated, the duration of the diffusion was 

 20 hours at the temperature of the cold room : — 



