.,o\C4Z 



BY J. M. PETRIE 



11. Bulb, pink cone 



12. Rhizome 

 13. 



14. ,, next roots 



15. Roots 



Orange in 1 hour, orange in 3 days. 



Negative after 3 days. 



Negative after 3 days. . 



Negative after 3 days. 



Red in 1 hour, dark red in 3 days. 



The glucoside disapj^ears on exposure to air: — When fresh 

 green leaves were exposed by being spread out openly on the 

 table, and tested at intervals, it was found that the reaction was 

 slower in starting as time proceeded, and after the fifth day of 

 exposure no more positive results were obtained. 



When this stage was reached, the addition of emulsin pro- 

 duced no effect, but after addition of a few drops of amygdalin, 

 a positive reaction was again obtained. 



These experiments prove that the enzyme still existed in the 

 plant after drying in air for five days, but that the cyanogenetic 

 glucoside had disappeared. 



That the glucoside should have such a short period of existence 

 after the plants are cut and collected, is unfortunate, since the 

 collection of a large quantity of material for the purpose of ex- 

 traction is thus rendered difficult. 



Summary: — The results of these experiments showed: — 



(a) That this Alocasia contained a cyanogenetic glucoside and 

 an enzyme. 



(b) Glucoside is contained in the leaves, stalks, roots, spathe, 

 ovary, and seeds, but it appeared to be quite absent from the 

 rhizomes, even from those portions of the latter immediately 

 contiguous to the roots. In some of the stalks it appeared to 

 decrease downwards towards the base till the bulbs were reached. 

 These bulbs gave indications of traces only of glucoside. 



The part of the plant used by the aborigines as food is the 

 soft pink core of these bulbs or swellings at the base of the 

 stalks, where the latter join the rhizome. The acrid juice is 

 first removed by washing or heating. It is important to note, 

 in this respect, that the suspected poisonous nature of the bulbs 

 does not appear to be due to hydrocyanic acid. 



(c) The cyanogenetic glucoside rapidly disappeared from the 

 leaves when they were left to dry in the air for a few days. 



