a aa TRANSACTIONS OF SECTION B. 343 
proportional to the fluidity of the solvent. It was assumed that the effect of 
fluidity on catalysis is similar to its effect on ionic mobility as determined by 
electrical conductivity. Hence by dividing the inversion velocity by the con- 
ductivity of the acid in the particular solvent the result obtained expresses the 
activity of the catalytic ion in this medium. In this way it was found that the 
activity was far greater in 70 per cent. alcohol than in water. 
It was therefore concluded that catalytic hydrolysis is retarded by the 
addition of water in the same way as esterification and other similar catalytic 
reactions. 
MONDAY, AUGUST 2A. 
The following Papers were read :— 
1. On Explosions in Gases (with Demonstration). 
By Professor H. B. Dixon, F’.R.S. 
2. Chemical Crystallography (with Demonstration). 
By Professor W. J. Popr, F.R.S. 
TUESDAY, AUGUST 25. 
Joint Discussion with Section M (Agriculture) on Metabolism.— 
See p. 663. 
The following Paper, opening a Discussion on Cyanogenesis in Plants, was 
then read :— 
The Cyanogeneltic Plants of New South Wales. 
By James M. Perri, D.Se. 
Of the plants growing in New South Wales, over a thousand species have 
been examined for hydrocyanic acid and cyanogenetic glucosides. Sixty of these 
gave positive results with sodium picrate paper. These include forty-four species 
native to New South Wales in seventeen Natural Orders. 
Some plants, well known to be cyanophoric in Europe, when grown in this 
State have never given any reaction, although tested in all seasons. 
Only a few were found to evolve free hydrocyanic acid, naturally, but all 
showed the presence of a glucoside and enzyme. 
When the natural enzymes in these plants were killed by boiling water, the 
reaction to sodium picrate paper ceased; if then a few drops of emulsin, pre- 
pared from sweet almonds, were added, positive reactions were again obtained, 
showing that in all cases the glucosides present in the plants were capable of 
being hydrolysed by emulsin. 
Of the sixty species stated, twenty are grasses, and these include eleven 
species indigenous to this State. The Sorghum vulgare examined by Dunstan 
and Henry was found to lose its glucoside when fourteen inches high, while the 
Australian-grown plant retains it when four feet high, and mature. Both 
glucoside and enzyme slowly disappear with air-drying. 
One hundred and fifty species of grasses were tested systematically for 
seasonal variations, and some were found to give negative results at particular 
seasons. ‘Two species of grasses alone evolved free hydrocyanic acid, and only 
one of these is available for grazing. This is the only one, except the sorghums, 
which has been associated with fatalities among stock. 
Among the non-cyanogenetic grasses, thirty-three species contained emulsin- 
like enzymes. 
