DISTllIBUTIOX OF TRUSSIC ACID IX THE VEGETABLE KINGDOM. 141 



•Fam. 207. Gramiaeffl. 



Glyceria aquatica ( — , Jorissen 1884). 



Panicum sp. div. {B., Briinnich 1003). 



Sorghum vulgare {B*., Dunstan-Henry 1902). 



Stipa hystricina, S. leptostachya (— , Hebert-Heim 1904). 



GYMNOSPERMiE. Fam. 208—210. 



CRYPTOGAMS. Fam. 211— . 



Fungi. 



? Hygrophorus agathosmus, H. cerasinus (? B.). 



Marasmius oreades (B., Loesecke 1871). 



? Pholiota radicosa (? B.). 



1 Russula foetens (? B.). 



The length of this list shows in a surprising manner that prussic acid, 

 a compound formerly supposed to occur only in the bitter almond, the 

 cherry laurel, and some related plants, seems to be distributed in widely 

 different natural orders. The dates given in the list indicate clearly that 

 our knowledge of this distribution is mainly of recent acquisition. This 

 is still more clearly shown if we consider only the cyanogenetic gluco- 

 sides so far isolated and either partially or fully investigated. 



1830. Amygdalin (Robiquet and Boutron-Charlard). 



1891. Linamarin, now known to be identical with phaseolunatin (Dunstan 

 Henry and Auld ') (Jorissen and Hairs). 



1901. Lotusin (Dunstan and Henry). 



1902. Dhurrin (Dunstan and Henry). 



1903. Phaseolunatin (Dunstan and Henry). 



1903. Corynocarpin (Easterfield and Aston). 



1904. Gynocardin (Power and Lees). 



1905. Sambunigrin (Bourquelot and Danjou). 

 1905. Prulaurasin (Herissey). 



The complete investigation of several of these cyanogenetic glucosides 

 has greatly enlarged our insight into the ways in which prussic acid is 

 combined in the plant. It is with pleasure I take this opportunity of 

 paying homage to these English researches so highly appreciated by 

 scientists throughout the world. 



This paper would become unduly long if I dwelt on every case of 

 cyanogenesis, with several of which I occupied myself personally. As an 

 instance of the difficulties attending the work may be mentioned a con- 

 troversy which arose over a single plant {Arum maculatum). The 

 Belgian chemist Jorissen, to whom we owe some interesting observations 

 regarding the distribution of hydrocyanic acid in plants other than the 

 Rosacese, mentioned in 1889 that on distilling Arum he found a small 

 quantity of prussic acid in the distillate, but other investigators were 

 unable to confirm this. When later I found prussic acid in some Javanese 

 Aracefe I wrote to Professor Plugge asking him to investigate Arum 

 maculatum. He thereupon completely confirmed Jorissen's results.'- A 

 short time ago I was informed by the well-k*iown plant physiologist, Dr. 

 Burck, who has long devoted attention tflfWTe biology of flowers, that the 

 trace of prussic acid in Arum plays a very special part in the biological 



' Proc. Boij. Soc, 1906, 78, 345. 



- Similarly, after much opposition, Jorissen waa shown to be right with regard 

 to tlie production of prussic acid by Hax. 



