46 Osazone Method for Detecting Sugars , &c . 
back on them when others are not available. Further, the osazone 
tests are of doubtful applicability in the case of mixtures of sugars. 
Such mixtures are present in plant cells. For these reasons vve felt 
and still feel that a claim (even if it is only a half claim) to distinguish 
between two sugars in plant tissue by means of the osazone test, 
when the two sugars yield the same osazone, is not very reassuring 
as to the degree of reliability of the results obtained, even if there 
is “ a question of the influence of viscosity upon molecular 
rearrangements, diffusion and crystal formation,” which results in 
the formation of different crystal aggregates. 
Nevertheless, readers might be excused for drawing from 
the section of Mangham’s paper headed “ Effects of Glycerine ” 
the conclusion that Mangham considered glucose and fructose to 
yield different osazones, for he speaks of “ dextrose and levulose 
phenyl osazones,” “ the two osazones,” “ the osazones.” Above 
all the description of Experiment III, in which “levulose and dex¬ 
trose phenyl osazones were added to pure glycerine ” and the 
behaviour of the resulting mixtures of osazone and glycerine 
compared, seems to assume the existence of two osazones, and the 
experiment appears to have for its object a determination of 
different properties of the two. In our opinion the use of the 
expression “ two osazones ” in Mangham’s paper for different forms 
of crystal aggregate of the same osazone is liable to misinterpre¬ 
tation, just as Mangham’s use of the symbols ‘ d\ and ‘ dl' to 
represent the types of osazone crystal aggregates yielded by 
glucose, fructose and sucrose respectively, does not conduce to 
clearness of thought when the symbols d, l and dl have a univer- 
ally accepted and quite different signification in sugar chemistry. 
However, as Mangham has now made his position clear, 
further discussion is unnecessary. With his conclusion that Senft’s 
reagent cannot be used to distinguish with certainty the individual 
sugars of a mixture we certainly agree. With regard to his further 
conclusion that this reagent is of considerable value in certain forms 
of research we feel some scepticism; it is a nice question whether 
it is ever worth while employing a bad method that can at best only 
give questionable results “ indicating probabilities rather than as 
affording demonstrations.” It appears to us that in many cases 
the result would be the expenditure of time in accumulating data of 
little value, accompanied by what is perhaps worse, a tendency to 
accept “ probabilities ” as facts. 
Ingvar Joroensen. 
Walter Stiles. 
