BY J. M. PETRIE. 117 



(9.) Alocasia zehrhia Koch and Veitch (Index Kew.). The 

 leaves and stalks resemble (4), but contain no cyanogenetic 

 glucoside. 



(10.) Colocasia antiquoritin Schott, (Prodr. Syst. Aroid., 1860, 

 p. 138), Index Kew. Cyanogenetic glucosides are absent from 

 the leaves and stalks. 



(11.) Colocasia antiquorimi Schott, vai\ esculeuta, Index Kew., 

 the "Taro" cultivated for food in the tropics, was also found to 

 be free from cyanogenetic glucosides. Samples of these plants 

 were obtained from the Botanic and University Gardens, and 

 also from a few private gardens. 



Those plants, in which it has just been stated that no cyano- 

 genetic glucoside was found, were afterwards tested by adding a 

 solution of amygdalin to the macerated material. In this way, 

 it was proved that all contained, in their leaves and stalks, an 

 emulsin-like enzyme capable of rapidly hydrolysing amygdalin. 



The Author desires to express his thanks to Sir Thomas 

 Anderson Stuart for the use of the laboratories for these ex- 

 periments, and to Mr. E. Cheel, of the Botanic Gardens, for con- 

 firming the names of the species. 



