Kd 
( 33 ) 
third experiment, cut in halves, to see whether they should yield 
more HCN. As no marked difference was to be noticed, there surely 
was no prussic acid that in the first two instances had remained 
unestimated. 
It was presently the turn of the opening buds to be studied. On 
the 2% of February cut branches of P. Padus, dipping in water, were 
placed on a well lighted spot in the hot house, the temperature being 
circa 20° C. After some weeks, a great number of buds had opened, 
and yielded shoots, which, though short, were nevertheless well fur- 
nished with leaves. 
5. 3. 02. 75 shoots taken; weight: 5,20 er.-HCN: 0.0079 er, i. e. 
0,15 °/,; in 100 shoots: 0,0105 er. 
> 
Cut branches placed in hot house 26. 2. 02. 
14. 3. 02. 60 shoots; weight: 8,70 gr-HCN: 0,0108 er.; i.e. 
0,12 °/,; in 100 shoots: 0,0180 gr. 
When one considers the weight of the shoots examined, it will be 
seen that in the second experiment they were more fully developed 
than in the first. It is clear that, as the shoots go on growing, a 
steadily increasing absolute amount of HCN-compounds gathers therein, 
so much so that even at a very early stage they contain three 
to four times the quantity found in the resting buds. As, on the 
other hand, the percentage of prussic acid depends on a number of 
circumstances, chiefly on the proportion of water in the shoots, a 
factor which itself is so very lable to modification, the changes under- 
gone by this relative amount of HCN are much less interesting. It 
will however be noticed that, notwithstanding the fact that the weight 
of the young shoots exceeds many times that of the buds, the per- 
centage of prussic acid is but feebly or not diminished. 
I should wish to recall here that Adm. and Lm. Tuma *), estimating 
the HCN in young leaf-buds of P. Padus, while these were opening 
in April, found no higher proportion than 0,05 °/,. This undoubtedly 
is due to the fact that the authors, distilling off after having added 
some sulfuric acid, did not obtain a complete splitting up of the 
elucosides. 
It will now be asked, whether the prussie acid which appears in 
the growing shoots is formed in the same, or perhaps transferred 
to them from the branches. As the green unfolding leaves will very 
probably begin to assimilate, it seems credible enough that the hydro- 
eyanic acid should be made by a process of “photosynthesis”. Whether 
1) Zeitschr. Allgem. Oesterr. Apoth. Ver. 1892, p. 330. 
Proceedings Royal Acad, Amsterdam. Vol. V, 
