1897 | BRIEFER ARTICLES 55 
tillation are collected, and tested with silver cyanide, isopurpurate (hot 
potassium and picricacid),and ammonium sulfocyanide. The action of 
the isopurpurate is especially characteristic. 
3. If these tests give negative results, it may be due to the absence 
of one of the generative principles. It is well, therefore, to repeat the 
experiments upon the seeds, crushing them in the presence of amyg- 
dalin and emulsin successively. 
As a result of such experiments I am able to make the following 
statements : 
1. Amygdalin and emulsin exist together in the seeds of Malus 
communis, Cydonia vulgaris, C. Japonica, Sorbus Aucuparia, and S. 
Aria. 
2. They do not occur together in the seeds of Pirus communis, 
Crategus oxyacantha, C. Azarolus, and Mespilus Germanica. 
The localization of emulsin and amygdalin in pomaceous seeds is 
difficult on account of the very small amounts in which they occur. 
L£mulsin.—This substance can be localized in these seeds only by the 
reagent of Millon. ‘The other tests for proteids and ferments give only 
negative or doubtful results. ‘The reagent acts very slowly. Place 
upon a slide a drop of Millon’s reagent diluted to one-fourth or one- 
fifth by water acidulated with nitric acid. In this mount the sections to 
be tested, and heat so that for at least seven or eight minutes nearly a 
boiling temperature may be obtained. The sections become rose- 
colored, at first exceedingly pale, but gradually deepening. When the 
color is quite uniform throughout, and the temperature is nearly that 
of boiling, the preparation is cooled and examined. The cells con- 
taining the emulsin are stained brown, all other cells being pale rose 
color. In this manner I have demonstrated that the emulsin occurs in 
numerous cells scattered through the parenchyma of the cotyledons, 
and especially in the vicinity of woody bundles, whose endodermis 
likewise contains it. It is entirely lacking, however, in the external 
Palisade cells. The hypocotyl, plumule, and root do not contain it, a 
fact that can be further demonstrated by detaching these regions and 
crushing them in a small quantity of amygdalin, when there is not 
developed the odor of almonds. 
Amygdalin.—Precise localization of this glucoside is impossible on 
account of its very minute quantity, which baffles the most delicate 
tests. It may be stated, however, (1) that this substance occurs in the 
cotyledons, since they contain the emulsin and by crushing develop 
