2^6 Sydney Mangham. 
ON SOME CRITICISMS OP THE OSAZONE METHOD 
OF DETECTING SUGARS IN PLANT TISSUES. 
By Sydney Mangham, M.A., 
Lecturer in Botany , Armstrong College , Newcastle-on-Tyne, 
in the University of Durham. 1 
S INCE the publication of two papers 2 dealing with the use of 
phenylhydrazine for locating sugars in plant tissues some 
criticisms of certain points dealt with have appeared, and have 
been quoted. As these criticisms seem to be based in part upon 
a somewhat inadequate appreciation of the significance of the 
observations recorded, I propose to attempt to emphasise here 
some points which I had hoped would have been clear to readers 
of the papers in question. 
In the interesting account by Davis, Daish and Sawyer 3 of 
their work on the carbohydrates of the mangold leaf a note 
appears 4 from which the following is extracted: 
“ It is difficult to understand Mangham’s view that it is possible 
to discriminate between dextrose and laevulose by means of the 
osazone test, seeing that both sugars (as well as mannose) yield 
identically the same osazone: Mangham seems to regard the 
osazones from dextrose and leevulose as distinct substances. 
“ In the writers’ opinion little reliance can be placed on a 
micro-chemical osazone test as a means of identifying maltose 
in plant tissues, owing to the presence of large quantities of 
other sugars. Our quantitative analyses (some 500 in all) have in 
no single instance disclosed the presence of even traces of maltose 
in the leaves or conducting systems of plants. In work of this 
kind micro-chemical tests as a means of distinguishing individual 
sugars should he avoided and only quantitative methods adopted. 
Otherwise contradictory and uncertain results are inevitable.” 
In their review of recent work on carbon assimilation Jorgen¬ 
sen and Stiles 5 make reference to the above criticisms, and add: 
1 Bacteriologist (Temporary), Naval Medical School, Royal Naval College, 
Greenwich. 
3 Mangham, S., 1911. “On the Detection of Maltose in the Tissues of 
certain Angiosperms.” New Phyt. 10, pp. 160-166. 
Mangham, 1915 “ Observations on the Osazone method of locating sugars 
in Plant Tissues. Ann. of Bot., XXIX, pp. 369 391. 
3 Davis, W. A., Daish, A. J., and Sawyer, G.C., 1916. “ Studies of the For¬ 
mation and Translocation of Carbohydrates in Plants. I. The Carbohydrates 
of the Mangold Leaf.” Journ. Agric. .Sci.. VII, pp. 255-326. 
4 l.c., p. 311. 
4 Jorgensen, I., and Stiles, W., 1917. 
Phyt. Reprint, No. 10, p. 128. 
“Carbon Assimilation,” New 
