20 FERMENTING POWER OF PURE YEASTS. 



to depict more strikingly the behavior of these organisms toward 

 the culture substance in this case apple juice. The weighings made 

 at stated intervals show the destruction of sugar through the loss 

 suffered by reason of the carbon dioxid given off. The weights 

 \vere taken each twenty-four hours and the results noted on the 

 record sheets. Fig. 4 depicts in a striking manner the daily loss of 

 carbon dioxid by the height to which the line designating the activity 

 of each yeast rises above the base. The chart is in fact a picture 

 of the vital activities of each yeast organism in the test. 



So. far as the weighings showed no change occurred during the first 

 twenty-four hours, but it is a fact, frequently verified by the writer 

 by microscopic examinations, that there results a large increase in 

 the number of yeast cells during the first day, but until the liquor is 

 fairly saturated with the carbon dioxid gas none is given off, and 

 therefore the destruction of sugar would not be shown by weighing. 

 The second day all the tests showed some loss, reaching 0.75 of a gram 

 in the case of the mixed culture. This greater activity was caused 

 by the larger amount of yeast sown. The next most active yeast is 

 No. 100. This is always the case when /S. apiculatus is compared 

 with other yeasts, and it is this precocity of development that ren- 

 ders it so obnoxious in the fermentation industries. In its final devel- 

 opment No. 100 makes a poor showing compared with the other 

 yeasts. Its maximum occurs on the fourth day at 2.05 grams, and on 

 the same day No. 37 reaches its maximum at 6.33 grams loss of car- 

 bon dioxid, though it was one of the slowest to start. 



Between these extremes lie all the other yeasts used, the mixed cul- 

 ture showing its climax at about half the height of No. 37. An inter- 

 est ing observation, which holds good in other tests, is that a mixture 

 of several pure yeasts has not show r n the same power of fermentation 

 that many of the same yeasts show when sown alone. In this partic- 

 ular case, and in fact whenever S. apiculatus is used, this result. 

 to a considerable extent, should probably be credited to the fact that 

 tins undesirable form is for a time dominant in the liquor to the 

 partial exclusion of more desirable ferments. 



MISCELLANEOUS ANALYSES OF FERMENTED MUSTS. 



During the several years that the tests of pure yeasts ami organ- 

 isms associated with them have been in progress many chemical 

 analyses of the fermented liquor have been made, and a number of 

 these analyses are presented in Table IV for reference. Generally 

 the yeasts do not show striking differences in the amount of alcohol 

 produced when used in the same must. There are, however, some 

 interesting differences, and these are brought out by the tabulated 

 analyses. This work was undertaken to collect preliminary data on 



