Detection of Maltose in Tissues of Angiosperms. 165 
visible at the end of five days, while with two hours’ heating there 
were signs of the formation of crystals from a yellow, syrupy liquid 
five days later. 
After six months the preparations were re-examined and a few 
cystals had then been formed. It therefore seems doubtful if Senft’s 
reagent is a very reliable one for the location of moderately weak 
solutions of cane sugar in plant-tissues, for the prolonged heating 
required to effect inversion promotes diffusion of the cell-contents. 
Quantitative results are therefore scarcely obtainable in this way. 
On the other hand the reagent forms osazones with extremely 
dilute solutions of levulose and dextrose' and so for these sugars 
provides a very delicate test. 
By employing carefully purified methylphenylhydrazine Grafe 
was able to distinguish between levulose and dextrose since this 
reagent only forms crystalline osazones with sugars containing the 
ketone group. These crystals were of a yellow-brown colour and 
quite distinct from those obtained with Senft’s reagent. With cane 
sugar Grafe found that his reagent produced the characteristic 
levulose methylphenylosazone after heating for an hour-and-a-half. 
Maltose yields a phenylosazone of a very definite character. 
Weak solutions, 1% to 5%, give after an hour’s heating dark yellow 
drops of liquid resembling treacle or “ Golden Syrup.” From these 
drops crystals of the osazone may form after some considerable 
interval—often several weeks. In colour these are a clear, lemon- 
yellow—not the golden yellow of the osazone formed from levulose 
or dextrose. The actual crystals are lamellate and very much 
larger than the fine, acicular crystals yielded by levulose and dextrose. 
They form rosettes or they may occur in dense, almost opaque 
masses which are recognisable with the naked eye. At the edge of 
such masses the typical maltose phenylosazone crystals can usually 
be made out (Figs. 3 and 4). Once formed the crystals are fairly 
unmistakable, but the apparent uncertainty of their production from 
the dark yellow syrup and their habit of forming in large isolated 
masses renders the exact location of maltose in plant-tissues rather 
difficult. 
In the course of an experimental investigation of the paths of 
translocation of sugars in plants, I have observed the occurrence 
1 '015% according to Grafe. 
2 Grafe, V. •* Studien iiber den mikrochemischen Nachweis ver- 
schiedener Zuckerarten in den Pflanzengewebe mittels der 
Pbenylhydrazinmethode.” Sitz. d. k. Akad. d. Wiss. in Wien, 
Mathem.-Naturw. ke., Bd. CXIV., Abth. 1, 1905, 115-128. 
