116 HYDROCYANIC ACID IN PLANTS, ill, 



(2.) Alocasia macrorrhiza var. variegata (Nicholson's Diet, of 

 Gardening). This is grown as an ornamental plant in the 

 Botanic Gardens. The leaves are green and white in large 

 patches; some of the leaves showed one half green and the other 

 half white. It was noted in testing these leaves that the green 

 portions always gave rapidly the hydrocyanic acid reaction with 

 the yellow paper, while the white portions showed either nega- 

 tive results, or only a faint colour-change after some time had 

 elapsed. The green stalks also gave rapid positive reactions. 



(3.) Another variety of this Alocasia, known as the "black 

 variety," and possessing dark green leaves, with veins and stalks 

 of a dark purple colour, was obtained from the Botanic Gardens. 

 When tested, the leaves and stalks of this plant showed absence 

 of hydrocyanic acid. 



(4.) Alocasia augiistiana Lindl. and Rod., (Nicholson's Diet, of 

 Gardening). This plant resembles (1) but has mottled stalks. 

 It yielded hydrocyanic acid when tested, and the reactions took 

 place rapidly with the leaves, more slowly with the stalks. 



(5.) Alocasia Sandtriana Bull, (Bailey's Cyclop, of Amer. 

 Hort.). The large arrow-head leaves, with undulating margins 

 and green veins, \vhen tested, gave a red and dark purple colour- 

 change in a few minutes; the mottled stalks also reacted very 

 rapidly. 



Two other Alocasias were tested, whose names still await 

 botanical confirmation, but which are apparently well-known to 

 horticulturists : — 



(6.) Alocasia intermedia, with leaves very similar to (5), but 

 with white veins, and red stalks, gave, with these organs, very 

 rapid and very strong reactions for hydrocyanic acid. 



(7.) Alocasia spectabUis, whose leaves resemble (1), but with 

 brown under-surface, and white veins, also gave strong and rapid 

 reactions with leaves and stalks. 



(8.) Alocasia metallica Schott, (syn., A. indica, Index Kew.), 

 (Bot. Mag. — description and coloured plate) gave negative results 

 in leaves and stalks. 



