( 35 ) 
Referring to what has been said with relation to P. Padus. the 
above given results require no further discussion. That in both 
species the percentage of HCN appears to be smaller in the etiolated 
shoots than in the green ones, has no very great importance. Etio- 
lated shoots indeed are known to contain much more water. the 
evaporation being less active under the opaque bell-jar. 
After it has thus been shown that buds opening in the dark also 
increase, as they grow, their amount of HCN, there still remain two 
ways of accounting for this augmentation. Perhaps the prussic acid — 
in whatever form it may be present — is made in the growing shoots 
out of other substances ; it could however be drawn from other parts 
of the plants; that is to say the branches in P. Padus, possibly also 
the leaves in the evergreen P. Laurocerasus. I regret not to have 
succeeded in establishing with certainty which of the two explanations 
is the right one. All I can say for the present is that the HCN 
gathering in the shoots is not derived from the internodes, which 
bear the buds examined. However, the possibility of the acid being 
supplied by more distant parts cannot at the present time be said to 
be excluded completely. 
In this part of the. research, I again chiefly made use of P. Padus, 
as this species, bearing no leaves in winter, was especially favourable. 
The point to be ascertained was whether the increase of HCN in the 
opening buds should be accompanied by changes in the adjacent 
internodes. 
In the first place the amount of HCN was determined in the inter- 
nodes below resting buds. As the length and thickness of these organs 
are exceedingly variable, it once more was necessary to analyse a 
not too small portion of plant-material. 
10. 2. 02. 100 internodes (Bot. G. Amsterdam) ; weight : 11,75 er.- 
HCN : 0,0108 gr, i. e. 0,09°/, ; in 100 internodes: 0,0108 er. 
7. 3. 02. 250 internodes (B. G.); weight : 18,95.-HCN : 0,0246 er. ; 
i. e. 0,13°/,; in 100 internodes : 0,0098 gr. 
With these amounts will be compared those observed in the inter- 
nodes below etiolated shoots. 
Branches (B. G. Amsterdam) placed in hot house 24. 2. 02., and 
covered by opaque bell-jars. 
17. 3. 02. 30 internodes are taken from below long etiolated 
shoots; weight: 3,85 gr-HCN 0,0057 gr; i. e. 0,15°/,; in 100 
internodes : 0,0190 er. 
Already this first experiment does not prove in favour of the view, 
that the HCN-compounds should be drawn from the adjacent inter- 
3* 
