114 



HYDROCYANIC ACID IN PLANTS, 111., 



(1.) Alocasia macrorrhiza Schott, (Prod. Syst. Aroid., 1860, 

 146) Index Kew., the "eunjevoi" of the aborigines. Specimens 

 of plants, growing wild in the bush, and cultivated in private 

 gardens, were tested for hydrocyanic acid. In all the fresh 

 leaves, the colour-change with picrate paper was observed to take 

 place within a few seconds. When the newly-cut leaves were 

 placed in a bottle without any reagent, the test-papers quickly 

 changed colour. 



Leaves which had become yellow and completely withered still 

 showed the reaction. 



Distributimi in the ])lant\ — The various parts and organs of 

 this plant were next examined separately. Uniform conditions 

 were observed throughout, as to quantity of material, size of 

 bottle, temperature, etc., and the time noted after which the 

 colour-change in the picrate paper was observed. 



Parts of one j)lant tested :- 



1. Leaves 



2. Leaf-stalks 



3. Bulb at base 



4. Rhizome 



0. Roots 



Stalks alone tested :- 



1. Midrib at tip 



2. Midrib at middle 



3. Midrib at base 



4. Stalk at middle 



5. Stalk at base 



Red in 1-5 minutes 

 Orange in 3 hours. 

 Pale orange in 3 hours. 

 Negative after 24 hours. 

 Red in o minutes. 



Red in 1 hour. 

 Orange in 1 hour. 

 Pale orange in 1 hour. 

 Negative after 12 hours. 

 Negative after 12 hours. 



Distribution in one jdant, from summit to base: — 



1. Leaves 



2. Green spathe 



3. Ovary 



4. Seeds 



5. Leaf-stalk, top 



6. , , lower 

 7. 



9. 



10. ,, base 



Red in 5 minutes, dark red in 3 days. 

 Red in 1 hour, dark red in 3 days. 

 Red in 1 hour, dark red in 3 days. 

 Red in 1 hour, dark red in 3 days. 

 Orange in 1 hour, dark red in 3 days. 

 Orange in 1 hour, dark red in 3 days. 

 Orange in 5 minutes, dark red in 3 days. 

 Red in 5 minutes, dark red in 3 days. 

 Red in 5 minutes, dark red in 3 days. 

 Red in 5 minutes, dark red in 3 days. 



