PRUSSIC ACID IN PLANTS 47 



stages of its growth, for it was found that lotusin is only present 

 in the young plant, and that as this matures the glucoside gradu- 

 ally diminishes in amount and finally disappears. 



It is worth noting that a similar glucoside appears to occur 

 in the allied plant Lotus austra/is, a native of Australia, which 

 has acquired some notoriety there as being poisonous to cattle. 



The cyanogenetic glucosides so far known fall naturally into 

 two classes — (a) those in which the cyanogen group is associated 

 with the non-sugar residue, and (b) those in which this group is 

 combined with the sugar residue. The essential difference in 

 the constitution of these two types may be represented graphi- 

 cally thus : 



Group A. 



/O C I2 H a O I0 



Amygdalin C u H 5 CH^ 



\CN 



/O C 6 H„O s 



Sambunigrin C 6 H 5 CH/ 



\CN 



(Benzaldehydecyandyhrin residue.) {Sugar residue.) 



/O C 6 H n 5 



Dhurrin C 6 H 4 (OH)CH< 



NCN 



(Parz-hydroxybensaidehydecyaH/tydrin residue.) (Sugar residue.) 



CHa /O C„H u O fi 



Phaseolunatin )C{ 



CH 3 / \CN 



(Acetonecyanhydrin residue.) (Sugar residue.) 



Group B. 



Lotusin C l5 H 9 5 O 



7CH.C n H,O l0 

 / 



CN/ 



(Lotojlavin residue.) (Sugar-cyankydrin residue.) 



The substances enumerated in the preceding paragraphs are 

 all the cyanogenetic glucosides so far definitely known, but there 

 can be little doubt that compounds of this type will eventually 

 be isolated from all the plants in which cyanogenesis is known 

 to occur. Allusion may be made here to two such plants, which 

 are of special interest. In Pangium edicle 1 Treub asserts that 

 prussic acid occurs in a free or in a very loosely combined state, 

 and he draws attention to the occurrence in the same plant 

 of a sugar possessing reducing properties which may be the 

 substance with which the acid is combined. No real attempt 

 has, however, yet been made to determine whether or not 

 1 Treub, Ann.jard. bot. Buitenzorg, 1896, vol. 13. 



