X. THE CHEMICAL CONSTITUENTS OF PLANTS 215 



(1) CaoH^O^N + H 2 = C, ; H 12 O ti + C 14 H 17 O 6 N 



Amygdalin. Glucose. Mandelic nitrile glucoside 



or prunasin. 



(2) C 14 H 17 6 N + H 2 = C 6 H 12 6 + HCN + C 6 H r ,CHO 



Prussic acid. Benzaldehyde. 



The first reaction can be effected by the enzymes, maltase present 

 in yeast and amygdalase present in emulsin, the second by the 

 enzymes, emulsin present in almonds and prunase present in plums 

 as well as in emulsin. Emulsin is capable of decomposing amygda- 

 lin, in one process (probably because it contains two enzymes) 1 into 

 the products, glucose (dextro-glucose), hydrocyanic acid and benzalde- 

 hyde. 



The last two substances, being volatile, are the chief constituents of 

 the essential oil of bitter almonds. 



Either amygdalin or some closely related substance occurs in the 

 seeds of many fruits, e.g., in those of the apple and of the mountain 

 ash berry. 



Elderberries (the fruit of Sambucus nigra) have been shown 2 to 

 contain a glucoside, sambunigrin, identical with the intermediate 

 compound, mandelic nitrile glucoside, formed in the hydrolysis of 

 amygdalin. 



Dhurrin was found in the common sorghum (Sorghum vulgar e) or 

 great millet. 3 It is present in the young immature plants, the amount 

 attaining a maximum when the plants are about a foot in height. On 

 hydrolysis by hot dilute acid, or by emulsin, it yields glucose, hydro- 

 cyanic acid and para-hydroxybenzaldehyde in accordance with the 

 equation 



C 14 H 17 O T N + H 2 O = C 6 H 12 O rt + HCN + C 6 H 4 (OH).CHO 



Young sorghum plants have often been known to be poisonous to 

 cattle, doubtless due to their yielding prussic acid, for the enzyme 

 necessary for the above hydrolysis is present in the plant. Many 

 plants related to the millets have been found to yield hydrocyanic 

 acid, e.g., Guinea grass (Panicum maximum) and maize (Zea mays), 

 but the quantity present is inconsiderable, even at the stages of growth 

 where it attains its maximum. 



Lotusin was obtained by Dunstan & Henry 4 from the leguminous 

 annual plant, Lotus arabicus, which, though poisonous at certain stages 

 of its growth, yields, near maturity, a valuable and harmless fodder. 



Lotusin is hydrolysed by heating with hydrochloric acid, or by an 

 enzyme, lotase, also present in the plant, with the following result : 



C 2S H 31 O 1(5 N + 2H 2 O = C 15 H 10 O, ; + HCN + 2C (V H 12 O 6 



Lotusin. Lotoflavin. d-glucose. 



Lotoflavin is a yellow dye resembling quercetin. 



Phaseolunalin, present in Lima or Eangoon beans (the seeds of 



1 H. E. and E. F. Armstrong and Horton, Proc. Eoy. Soc., May 16, 1912. 

 8 Bourquelot and Danjon, Compt. rend., 1905, 141, 598. 



3 Dunstan & Henry, Phil. Trans., 1902, A. 199, 399. 



4 Phil. Trans., 1901, B. 194, 515. 



