628 HYDROCYANIC ACID IN PLANTS, U., 



No free hydrocyanic acid was evolved from the grass on keeping 

 in a closed bottle for three days. 



Andropogon australis has not shown the least trace of hydro- 

 cyanic acid at any time of the year. 



These two grasses are the only two indigenous sorghums, syn. 

 respectively with Sorghum halepense Pers., and S. plumosum 

 Beauv. 



Andropogon sorghum, vars. vulgaris, saccharatus. — Grown in 

 experimental plots these grasses were tested in each month, and 

 gave positive reactions from January to December. There was no 

 period in which healthy growing plants were free. In only one 

 plot growth was arrested, and the plants killed, by cold weather 

 in June, and within a few days the tests varied from "strong" to 

 "faint" and nil, the height being 14 inches. Dunstan and Henry 

 found the Egyptian sorghum to lose its glucoside entirely when 

 14 inches high, while, on the other hand, the sorghum grown here, 

 on the Richmond River, and also that grown in Queensland, 

 showed the presence of glucoside when over 4 feet high. 



The glucoside was present in the inflorescence, leaves, stems, and 

 roots. The top leaves were always strongest, and especially the 

 young uncoiled apex-leaves; the reaction diminished with the posi- 

 tion of the leaves down the stem, and frequently the lowest leaves 

 gave none. The stems, too, showed a gradual diminution 

 downwards, though frequently they gave uniform reactions. In 

 the roots the strongest reaction was often obtained from the 

 extreme tips. 



The leaves also showed a remarkable variation in enzyme, 

 as the following summary of the results, obtained from tests on the 

 leaves of mature plants, will show : — 



i. Leaves anaesthetised, showed strong positive reaction, 



emulsin added — no evident change produced, 

 ii. Leaves anaesthetised, showed faint positive reaction, 



emulsin added — no evident change produced. 



iii. Leaves anaesthetised, showed faint positive reaction, 



emulsin added — very strong positive reaction. 



