292 
AMERICAN JOURNAL OF BOTANY 
[Vol. 10, 
In the present experiment some samples of apple extract were submitted 
to the fermentative action of 5 . marxianus . 8 This yeast grew very well 
in the extracts after a slight adjustment of acidity. A period of 45 days 
at 26 to 30° C. was allowed for complete fermentation. Examination of the 
cultures then showed that very little reducing substance had escaped 
fermentation. Later, when the residual reducing power of such cultures 
was compared with that of other cultures which had been fermented with 
baker’s yeast, the values were so similar as to warrant the assumption that 
the residual reducing power of the former was due to free pentoses only, 
and that maltose was, from the quantitative aspect, a negligible quantity. 
Summary and Conclusion 
The present paper calls attention to a possible misinterpretation of 
analytical data by Mitra; namely, that the increased reducing power of 
an apple extract after complete inversion is due to maltose, while the 
writer believes it to be due to the hydrolysis of phloridzin. In support of 
this latter viewpoint, the paper has presented the following points for 
consideration: 
1. Phloridzin is a normal constituent of apple bark and maltose has not 
been shown to be. 
2. Pure phloridzin is completely hydrolyzed to glucose and phloretin 
under the conditions of the Darwin and Acton method used by Mitra. 
3. Phloridzin in mixtures of sugars behaves similarly to maltose, and 
can be quite as accurately determined by the Darwin and Acton method. 
4. This method when applied to apple tissue gave values which, when 
interpreted as either phloridzin or maltose, agreed closely with those re¬ 
ported by Mitra, using similar methods and material. 
5. The direct determination of phloretin in apple tissue gave phloridzin 
percentages comparable with those obtained by means of glucose ( i.e ., by 
the method of Darwin and Acton). Thus it was shown that the increased 
reducing power of apple tissue after a ‘‘complete inversion” is due to 
phloridzin and not to maltose. 
6. An application of the fermentation method of David and Daish 
failed to show the presence of detectable quantities of maltose. 
In conclusion, the writer wishes to repeat that these statements simply 
call for a reconsideration of the maltose values reported by Mitra and do 
not necessarily show that his material did not contain maltose, seeing that 
his was younger, probably of a different variety, and from a different 
8 The culture of Saccharomyes marxianus was procured through the kindness and 
cooperation of Professor G. V. Copson of the Department of Bacteriology. In cooperation 
with Professor Copson, the culture was thoroughly tested as to its fermentation charac¬ 
teristics and found to behave normally, that is to say, it readily fermented all the common 
sugars except maltose. Later the Bacteriological Department aided in the cultivation of 
the yeast in the extracts of apple tissue. 
