598 



POPULAR SCIENCE MONTHLY. 



would mean that up to a very liigh limit of concentration alcohol 

 is absolutely harmless, that at a certain point it becomes suddenly 

 toxic, and that slight increase beyond this concentration worked 

 very rapidly to bring growth to a standstill. 



A second possibility would be represented by a straight line, 

 "Z," dotted line, falling uniformly from zero per cent to fourteen 



r 



4 Hours 

 I Count,' 



22 

 41 



Of^ 2061 



ALCOHOL. 



%oX^ 



69" 



28 45 51 72 



III IV V VI 



GROWTH OF^ YEAST. 



Fig. 2. G. C, curve of a jrenmctrical progression increasing at the rate of yeast growth in the 

 normal cultures for tlie first twenty-four hours. The numbers at the right indicate the 

 number of torulcz found in a cubic millimetre of the difTcrcnt cultures. 



per cent. This would indicate that the effect of the presence of 

 alcohol in the culture medium upon yeast growth was a purely 

 mechanical effect, a matter of friction, a clogging of the molecules, 

 as it were. This would signify, the less alcohol the better, but 

 that a small quantity has a comparatively slight effect, and that 

 probably no harm is done in the way of changing the chemical 

 reactions concerned in the growth processes of the yeast plant. 



A third possibility, represented by dotted line "Y" in the 

 figure, is in line with an idea not infrequently carried into prac- 

 tice, viz., that a little alcohol increases, " stimulates," activity, a 

 larger quantity interferes with it. If this were found to be the 

 case, the important matter to determine would be at what point 

 of concentration alcohol ceases to be beneficial. 



The heavy line, " M," represents the fourth possibility, viz., 

 that minute amounts of alcohol have relatively a much greater 

 retarding effect upon the growth of yeast than larger amounts. 

 The line is plotted from the results of a series of experiments, 

 of which a different expression is given in the diagram to the right 

 in the figure. One thousandth of one per cent is seen to cause 



