296 
president's address. 
Dunstan and Henry make the following remarks with 
reference to the part these bodies play in plant metabolism: — 
“ The occurrence in Phaseolus lunatus, apparently 
throughout its life history, of a cyanogenetic glucoside, 
together with the enzyme appropriate for its hydrolysis, 
seems to strengthen the view that these glucosides must 
play some definite part in the metabolism of plants. 
“Treub, as the result of his investigations of the produc- 
tion and distribution of hydrocyanic acid in Pangium edule, 
suggested that the immediate precursor (probably a cyano- 
genetic glucoside) of the acid in this plant is a formative 
material utilised in the synthesis of proteid. In this 
connection, it is of interest to note the ease with which 
cyanogen compounds of this type can, by processes of 
reduction, be converted into amino-derivatives, which recent 
researches indicate as the materials from which (by processes 
of condensation) proteids originate. This supposition implies 
that cyanogenetic glucosides are to be regarded as plastic 
unstable materials, whilst the enzymes with which they are 
associated must be considered as aplastic or stable sub- 
stances, with the definite function of decomposing, and 
possibly also producing cyanogenetic glucosides, since the 
hydrolytic action of enzymes appears to be reversible. 
“ This suggestion may explain the occurrence of cyano- 
genetic glucosides in Lotus arabicus and Sorghum vulgare 
during that period of their life-history in which metabolism 
is active, and their disappearance when the plants have 
matured and produced seeds, since this period coincides with 
that in which the synthesis of proteid in the plant is actively 
proceeding. Although Phaseolus lunatus resembles Lotus 
arabicus and Sorghum vulgare in containing a cyanogenetic 
glucoside, it differs from these plants in continuously 
secreting this glucoside, which is likewise found in the seeds. 
In this respect Phaseolus resembles the bitter almond. The 
seed produced by Phaseolus lunatus under cultivation, how- 
