BY JAMES M. PETRIE. 629 



iv. Leaves anaesthetised, gave negative result, 



emulsin added — very strong positive reaction, 

 v. Leaves anaesthetised, showed negative result, 

 emulsin added — negative result, 

 amygdalin added — strong positive result. 

 In i. and ii. class of results we have apparently an abund- 

 ance of enzyme, in iii. a deficiency, and in iv. entire absence. In 

 iv., certain leaves, chiefly the lowest on the stems, contained gluco- 

 side alone, the accompanying enzyme having entirely disappeared. 

 In v., certain leaves are shown to contain enzyme only, without 

 glucoside. 



The mature plants when cut, and exposed to the air to dry, 

 undergo very little change, with regard to glucoside or enzyme, 

 during the first week. After this, the glucoside is gradually hydro- 

 lysed ; but while this action is proceeding, the enzyme, too, appears 

 to be slowly destroyed, and so it happens that sometimes it is the 

 glucoside, at other times the enzyme, which first disappears. 



Andropogon gryllus. — This indigenous grass never shows more 

 than a trace of glucoside, and that only in the winter; during the 

 hot summer weather it contains none. In autumn, the flowers and 

 also the isolated seeds gave positive reactions. 

 January - (young and green). August ... -f faint. 



April + faint. November ... + very faint. 



Andropogon intermedins and A. ischcemum are two native 

 grasses, which are closely related, and in the summer months give 

 strong reactions for a cyanogenetic glucoside. 



intermed. ischcem. 



January... ... + strong ... ... + strong. 



April ... ... + faint -... ... + faint. 



August ... ... + faint ... ... + faint. 



November ... + strong ... ... + faint. 



Andropogon micranthus. — At no period was more than a trace 

 of hydrocyanic acid detected, even throughout the flowering season, 

 and during the winter months the grass was entirely free. 

 January ... + faint. August ... - 



April... ... + faint. November ... + faint. 



