377 
) 
of locating Sugars in Plant Tissues . 
The io per cent, mixture of cane sugar yielded rather dense, lumpy 
clusters of crystals. The amount increased for a time, but the final yield 
was much smaller than that given by either of the i per cent, mixtures of 
the constituent hexoses. 
The io per cent, mixture of maltose yielded crystals after standing for 
two or three days. The amount increased for some days, and the crystals, 
which were quite distinct in form, appeared to arise from the drops of 
syrupy liquid mentioned above. The presence of finer crystals in smaller 
quantity rather suggests that a certain amount of the maltose had under¬ 
gone hydrolysis with the production of dextrose. Glycerine has, indeed, 
been shown to have a hydrolytic action upon cane sugar and upon 
maltose. 1 
It is, however, apparent that in the case of the i per cent, mixture of 
cane sugar hydrolysis had not proceeded sufficiently to cause a precipitation 
of osazones from the resulting invert sugar. 
On the other hand, after the io per cent, mixture had been heated for 
an hour, enough of the cane sugar had become hydrolysed to produce 
a good crop of crystals. 
It is clear, then, that attempts to distinguish cane sugar qualitatively 
in presence of its constituent hexoses by comparing the yields of osazones 
obtained in duplicate preparations, only one of which has been heated, 2 
cannot give trustworthy results, since the formation of a precipitate with 
cane sugar demands its presence in a relatively high minimum concentration 
if the duration of heating is not to be prolonged unduly. 
Still less reliability attaches to the method as a quantitative one, for 
from the above examples it is evident that after heating for one hour 
similar osazone yields would result if each of the pair of preparations con¬ 
tained both dextrose and cane sugar in i per cent, strength. Indeed the 
presence of cane sugar, in addition to the hexose, would not be detected by 
eye any too readily unless present in several times the above amount. 
That Senft was led to attach too much importance to this method of 
attempting to distinguish cane sugar doubtless arose from using 50 per cent, 
sugar solutions, 3 and apparently neglecting to check the results so obtained 
by comparison with those given by weaker solutions more comparable in 
concentration with the contents of plant cells. 
To a certain extent the work of Strakosch, 4 who employed the method 
in an investigation on the sugars of the beet, is open to criticism on the 
grounds of unreliable technique, and only those of his conclusions with 
1 Donath (’ 94 ). Grafe records (’ 05 , p. 21) that maltose undergoes some hydrolysis after 
i-i| hours heating with Senft’s reagent. 
2 Hexoses alone slowly yield osazones in the cold. 
3 Senft, 1 . c., p. 10. 
4 Strakosch (’ 07 ), p. 862. Cf. also Ruhland (’ 12 ), pp. 219-22, for criticisms. 
c c 
