( 34 ) 
this is the case or not will easily be ascertained by analysing shoots 
developed in the dark. 
Branches of P. Padus, placed in the hot house 10. 2. 02., covered 
by a blackened box. After some weeks, numerous etiolated shoots 
had been developed. 
5. 8. 02. 50 short shoots taken; weight: 5,40 er.-HCN: 0,0061 
er, i.e. 0,11 °/,; in 100 shoots: 0,0122 gr. 
Branches put in the dark 24. 2. 02. 
17. 3. 02. 30 well grown, etiolated shoots, for the most part } — 
1 dM. in length; weight: 7,90 gr.-HCN: 0,0054 gr; i.e. 0,07 °/,; 
in 100 shoots: 0.0180. gr. 
There can be no doubt, from the results given above, that shoots 
erown in the dark also contain a much larger quantity of HCON-com- 
pounds than the resting buds, and that these substances cannot have 
been built up by an assimilatory process, under the action of sunlight. 
Results of quite the same kind were obtained in studying prunus 
Laurocerasus. 
Resting buds.-28. 12. Ol. 115 buds, mostly axillar (from the growers 
of medicinal plants GROENEVELD and Linprour, at Noordwijk); weight: 
1,65 er.-HCN: 0,0040 gr; i.e. 0,24 °/,; in 100 buds: 0,0035 
Shoots developed in the light (also mostly from axillar buds).-24. 4. 
or. 
02. 50 shoots, still short, eut from the shrubs growing in the Botan. 
G. Amsterdam; the pale green leaves are not quite unfolded; weight: 
9,30 gr-HCN: 0,0278 er, i.e. 0,30 °/,; in 100 shoots: 0,0556 gr. 
27. 4. 02. 50 shoots, younger than the former, or newly opened 
buds; weight: 4,90 er-HCN: 0,0138 gr.; 1. e. 0,28°/,; in 100 
shoots: 0,0276 er. *) 
Etiolated shoots. — Branches of P. Laurocerasus (B. G. Amsterdam) 
placed in the hot house, under blackened cylinders 23. 4. 02. 
10. 5. 02. 5 shoots taken; weight: 2,25 gr.-HCN: 0,0047 er. ; 
i. e. 0,21°/,; in 100 shoots: 0,0940 gr. 
Branches in the dark 25. 4. 02. 4. 5. 02. 10 very short shoots; weight: 
1.65 er-HCN: 0,0087 gr. i. e. 0,22°/,; in 100 shoots 0,0370 gr. 
Branches in the dark 27. 4. 02. 12. 5. 02. 11 shoots; weight: 
4.70 egr.-HCN : 0,0083 gr.; i. e. 0,18°/, ; in 100 shoots : 0,0755 gr. *) 
1) A. J. van pe Ven. (Cyaanwaterstofzuur bij de Prunaceae. Dissertation 
Amsterdam. 1898; also Archives Néerlandaises, 2e Série, tome II, 1899 (reports 
(p. 34 resp. p. 391) for young shoots 0,19-0,23"/. 
2) Van DE Ven (1. c. p. 37 resp. p. 393) applying the test of Gresnorr—TRevs, 
was not able to detect prussic acid in etiolated shoots of P. Law ocerasus, This 
affords a new proof that microchemical reactions, as soon as the substarces are 
not very abundant, necessarily require analytical confirmation. Mostly so when the 
test yields negative results. 
