June, 1923] HARVEY — MALTOSE IN APPLE TISSUE? 2 QI 
different lots of control, or untreated, summer shoots. In the table are 
included also the percentages of maltose reported by Mitra for tops of 
two-year-old apple seedlings on approximately corresponding dates. There 
is a striking similarity between the writer’s maltose values and those 
of Mitra. 
If it can be shown that the writer’s values are really for phloridzin and 
not for maltose, there should be some hesitancy in accepting Mitra’s values 
as maltose. 
That the former figures are due to phloridzin is made quite clear by 
the two experiments reported below. 
Estimation of Phloridzin hy Means of its Product , Phloretin. In order 
to ascertain the exact contribution of maltose to the increased reducing 
power of apple extracts after “complete inversion,” a method was devised 
for determining phloridzin by means of its hydrolytic product phloretin, 6 
instead of by its glucose. A sample of apple extract after complete in¬ 
version yielded 0.148 gram of phloretin, which should correspond to 0.2356 
gram of anhydrous phloridzin. This quantity of phloridzin should the¬ 
oretically yield 0.0972 gram of glucose. On the same extract the increased 
reducing power was also determined and calculated as glucose. The 
glucose found was 0.0932 gram, a quantity which is strikingly equivalent 
to the phloretin found by the other method. The amount of phloridzin 
present as estimated by its phloretin and its glucose products were 2.36 
and 2.27 percent respectively. The amount of maltose in the apple tissue 
examined must therefore be extremely small. 
Estimation of Maltose hy Fermentation with the Yeast , Saccharomyces 
marxianus . Finally, in order to be more certain regarding the question of 
occurrence of maltose in apple tissue, examination was made for maltose 
by the method suggested by David and Daish. 7 These authors found 
that maltose could be quantitatively determined most accurately in plant 
extracts by the aid of special yeasts, which are unable to ferment maltose 
but readily ferment hexoses, sucrose, and other lower hexose derivatives. 
Of such yeasts there are several species, but from numerous tests they were 
able to designate three species as especially useful: namely, Saccharomyces 
marxianus , S. anomalus , and S. exiguus- After plant extracts have been 
submitted to fermentation by these yeasts, the residual sugars are assumed 
to be maltose and pentoses. Differentiation is then made between pentoses 
and maltose by a further fermentation with ordinary baker’s yeast which 
leaves the pentoses only. 
6 The new method is extremely simple as here employed. The apple extract is carried 
through the regular procedures of analysis, including the complete-inversion treatment. 
Upon cooling and neutralizing after complete inversion, the phloretin separates quanti¬ 
tatively as an amorphous white precipitate which is readily filtered on a Gooch crucible, 
dried in a vacuum oven at 95-100° C., and weighed. 
7 Loc. cit. 
