440 TRANSACTIONS OF SECTION B. 
5. When dried in vacuo over sulphuric acid and subsequently immersed in 
water. 
Further blackening occurs in solutions of salts such as sodium chloride, sodium 
sulphate, &c., which are not considered as hormones by Professor Armstrong. 
The time of blackening of leaves immersed in such solutions varies with the con- 
centration of the solution. A similar variation in time of blackening also occurs 
when leaves are immersed in varying concentrations of alcohol. 
These experiments show that not only anesthetics but a variety of other 
agencies are capable of producing the blackening in question. The only 
character which these agencies appear to have in common is, not that they are 
activators of enzymes, but that they bring about those complex changes which, 
owing to the fact that they mainly await analysis, have to be classed together 
as death of the tissues. It follows then that the blackening is probably a 
secondary phenomenon related to the death or injury of the leaf. 
It is well known that in the case of the plant-cell one of the most striking 
changes which occur at death is a great increase of permeability of the cell. 
The simplest explanation, then, of the blackening, and the one most consistent 
with the present state of our knowledge, would seem to be that put forward by 
Maquenne and Demoussy in 1910, that the blackening occurs as a result of 
changes of permeability within the tissue, whereby the enzymes are brought into 
intimate contact with their substrates. 
7. Action of the Enzymes of Emulsin on Amygdalin and Vicianin. 
By A. Compton, 
MONDAY, SEPTEMBER 9. 
Joint Discussion with Section A on the Atomic Heat of Solids. 
See p. 407. 
The following Papers were then read :— 
1. Synthetic Aminoglucosides. By Professor J. C. Irvine and 
A. Hynp, M.A., B.Sc. 
In recent publications’ the authors have described the preparation of 
bromotriacetylglucosamine hydrobromide and the use of this compound in pre- 
paring a methylglucosamine which was shown to be o-aminomethylglucoside. 
Further experiments have now indicated that bromotriacetylglucosamine is a 
general reagent for the preparation of a-aminoglucosides, as it enters into reaction 
with widely different types of hydroxy-compounds giving, in the first instance, 
acetylated aminoglucosides from which the acyl grovps may be removed by 
hydrolysis. 
So far as is known at present, the a-aminoglucosides thus obtained do not 
occur naturally, and they are distinguished from unsubstituted natural or 
artificial glucosides by their alkalinity, their capacity to form additive salts with 
acids, and their behaviour towards hydrolytic reagents. Some of the com- 
pounds are remarkably stable, and are only decomposed into a salt of glucosamine 
when strongly heated with concentrated acid. In such cases the compounds are 
also unaffected by enzymes, and form molecular complexes with metallic halides. 
From these and other considerations, a-aminoglucosides of this nature are 
regarded as cyclic nitrogen compounds of the general type :— 
R 
HSN —0 
HZ 
CH,OH . CHOH . CH . CHOH . CH .CH 
| 
SSS 
* Chem. Soc. T'rans., 1911, 99, 250; 1912, 101, 1128, 
———— 
