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Botany. — “On the prussic acid in the opening buds of Prunus.” 
By Prof. B. Verscnarrent, (Communicated by Prof, Hugo 
DE VRIES). 
During last winter and the spring of 1902 I made a series of 
determinations to ascertain the amount of hydroevanie acid which 
can be prepared from different organs in species of Prunus. They 
were untertaken with the view of investigating the changes that 
occur during the budding, regarding the prussic acid-compounds. 
In these analyses the titration-method of Lrepig was always used in 
the following manner. The parts of the plants to be examined — mostly 
D_— 15 vers. freshly gathered material, — were heated in 200—300 em? 
of water to 60° C., so as to kill the protoplasm without destroying 
the emulsin. Though it will directly be shown that this treatment 
answers the purpose, the heating to 60° was repeated after some 
hours or the next day, to be certain that no cells were still living. 
Between both treatments and also during 24 hours after the second 
heating, the organs remained, immersed in water, in a well corked 
flask, that the emulsin might have time to splitcompletely the HCN- 
glucosides. After that, the distillation was performed, the prussic 
acid being collected in a little flask containing some drops of KOH- 
solution, and the titration was made after the method deseribed in 
the treatises, with */,, normal nitrate of silver. The distillate was 
always collected in a flask of 100 em.” capacity; by taking with a 
pipette a known volume, I was able to repeat the titration two or 
three times in the same experiment. The quantities of plant-material 
and water being as above, it appeared without exception that the 
whole of the prussic acid had been condensed together with the first 
100 em.” of water. 
The necessity of allowing the objects to macerate for some time 
after the killing is clearly shown by the following preliminary 
experiment. 
From 25 leaves, one year old, of Prunus Laurocerasus (Bot. G. 
Amsterdam) gathered 9. 12. Ol. the halves of the blades were cut 
on each side of the middle-nerve. The halves a weighed 11,85 ers, 
the halves 5 11,35 ers. The first portion was immediately submitted 
to distillation after having been immersed in the proper quantity of 
water, and gave 0,0160 grs. HCN. The portion 4 was heated to 60° 
C., and remained under water till the next day ; this time the amount 
of HCN was 0,0254 gr. As soon however as both portions are 
treated as 6, the concordance of the results is very satisfactory : 
