PRUSSIC ACID IN PLANTS 43 



almond, immediately after germination, yields considerable 

 quantities of prussic acid (probably produced by the decom- 

 position of amygdalin), and that the quantity of acid yielded 

 by the embryo steadily increases to a maximum. It is inter- 

 esting in this connection to point out that the seeds furnished 

 by wild Phascolus lunatus yield, like bitter almond seeds, con- 

 siderable quantities of prussic acid, whilst those produced by 

 the cultivated P. lunatus resemble sweet almond seeds in 

 yielding only traces of the acid or none at all. 1 If these can 

 be regarded as strictly parallel cases, it would appear that 

 possibly the sweet almond may have been produced by the 

 cultivation of the bitter almond. 



It has been asserted that amygdalin occurs in other plants 

 besides the two varieties of almond, 2 and in particular a so- 

 called " amorphous amygdalin " has been regarded as the source 

 of the benzaldehyde and prussic acid yielded by cherry-laurel 

 leaves when macerated in water ; 3 and the same product was 

 stated by Greshoff 4 to be present in Gymnema latifolium, Pygium 

 parviflorum, and P. latifolium, and by others 5 in the seeds of 

 various rosaceous plants, such as Mains communis, Cydonia 

 vulgaris, C. japonica, Sorbus Aria, and S. Aucuparia. With the 

 exception of Gymnema latifolium, in which no emulsin was 

 detected, all these plants were stated to contain both emulsin 

 and amygdalin ; but the evidence adduced of the presence of 

 the glucoside is usually merely the production of benzaldehyde 

 and prussic acid from the seeds after maceration in water. The 

 fact that such evidence is insufficient to warrant the conclusion 

 that amygdalin is present in any particular case has been illus- 

 trated recently by Bourquelot and Danjou, 6 who have shown 

 that the berries of the common elder {Sambucus nigra), which 

 3 r ield benzaldehyde and prussic acid on maceration in water, 

 contain not amygdalin but a new glucoside, sambunigrin, which 

 is isomeric with the mandelic nitrile glucoside of Fischer. 



Dhurrin. — This substance, which is closely related chemi- 

 cally to the three glucosides referred to in the preceding 



1 Dunstan and Henry, Proc. Roy. Soc. 1903, 72, 285. 

 3 Greshoff, Ber. der Deutsch. Chem. Ges. 1890, 23, 3548. 



3 Lehmann, U ber das Amygdalin, 1876. 



4 Greshoff, loc. cit. 



5 Lutz, Repertoire de F 'harm. 1S97, 312. Riegel, Ann. Chem. Pharm. 48, 361. 

 Wicke, ibid. 79, 81 ; 81, 241. 



6 Compt. rend. 1905, 141, 598 ; cp. Guignard, Compt. rend. 1905, 141, 236. 



