IS IT MALTOSE OR PHLORIDZIN THAT IS ABUNDANT IN 
APPLE TISSUE? 
E. M. Harvey 
(Received for publication September 25, 1922) 
A recent paper by Mitra 1 on the seasonal changes of certain carbo¬ 
hydrates in apple trees, records the presence of very considerable quantities 
of maltose (0.6-5 percent) and discusses its behavior in relation to tempera¬ 
ture, acidity, and enzym activity. That maltose should be so abundant 
in apple tissue is, alone, a point of great interest, and, adding thereto 
Mitra’s data on seasonal fluctuations of this sugar and his explanations of 
such fluctuations, the whole constitutes a very important contribution to 
our knowledge of the physiology of the apple tree, should his findings be 
substantiated. Such striking conclusions as the following, quoted from 
Mitra’s publication, would seem to deserve considerable attention: 
The translocation of sugars in apple spurs is largely in the form of glucose and maltose. 
. . . Maltose appears to be the most important sugar of translocation during starch ac¬ 
cumulation in autumn. To sum up, the upward translocation of sugar in spring is largely 
in the form of glucose, while translocation of sugar from leaves to stem in autumn is largely in 
the form of maltose. . . . Maltose is most abundant and glucose is least abundant in summer 
and autumn, when acidity is highest and nearer the optimum for diastase than for maltase. 
On the other hand, maltose is lowest and glucose highest during the dormant period, when 
acidity is lowest and nearer the optimum for maltase than for diastase. . . . These facts 
suggest an explanation of why maltose is the most important sugar of translocation from 
leaves to stem in summer. 
The significance of the above-quoted conclusions for plant physiology 
and theoretical horticulture is apparent and justifies a rather close scrutiny 
into the methods and material from which they are derived. The present 
paper is an examination of the maltose situation in the apple as reported 
by Mitra, and presents reasons for a reconsideration of his data respect¬ 
ing it. 
The large figures reported by Mitra for maltose led the writer to an 
examination of the method and conditions under which his analytical data 
for maltose were probably obtained. At the outset, however, this critical 
attitude arose largely through the writer’s own experience of several years 
in the analysis of apple tissue, although many of the statements to follow 
are based on subsequent specific study of the question. 
The method employed by Mitra for maltose was that described by 
1 Mitra, S. K. Seasonal changes and translocation of carbohydrate materials in fruit 
spurs and two-year-old seedlings of apple. Ohio Jour. Sci. 21: 89-103. 1921. 
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