BY JAMES M. PETRI E. 823 



united to the cyanogen-group, the third residue being the loto- 

 flavin dye. 



Fischer(77) has shown that the glucosidoclastic enzymes may be 

 divided into two classes according to whether they act on gluco- 

 sides derived from a-glucose or /3-glucose(78) respectively. The 

 glucosides, therefore, exist in two stereo-isomeric forms, viz., a- 

 and /3-alkyl ethers of the hexoses, and the enzymes are corres- 

 pondingly described as a- and /3-enzymes. Asa type of the first 

 class the maltase of yeast may be taken, and of the second the 

 emulsin of bitter-almonds. It would seem that a certain relation- 

 ship must exist between the configuration of the glucoside and 

 that of the enzyme which is capable of hydrolysing it, although 

 the latter need not be specific in each case. Dunstan and Henry 

 have also shown that their phaseolunatin is the only natural 

 a-glucoside(79) so far obtained, all others yielding the /3-hexoses on 

 hydrolysis by enzymes; but the two sugar-molecules of amygdalin 

 appear to be a and /3, the former alone being liberated by maltase. 

 Concerning the significance of these compounds in plant-physi- 

 ology, we have some interesting investigations by Treub and 

 Soave, who discarded the old idea of protective poisons and waste- 

 products, and raised them to a higher level. Treub(80) found 

 both free hydrocyanic acid and glucoside existing together, and 

 by increased assimilation there follows an increase in the amount 

 of both. Soave(81) showed that hydrocyanic acid first appears in 

 the seed at the commencement of germination, and that the 

 amygdalin is a reserve-substance of the seed. The results of 

 Weevers(82) also show that many glucosides may act as reserves. 

 The conclusions of these investigators are, that the cyanogenetic 

 glucosides are transitional substances assimilating the inorganic 

 nitrogen compounds and supplying the plant with food through 

 the medium of the cyanogen-group. 



These resultslend further support to the hypothesisof Latham(83) r 

 who has shown how the formaldehyde of plants and the ammonia 

 from the roots may give rise to hydrocyanic acid, and how the 

 latter unites with formaldehyde to form a series of cyan-alcohols, 

 through which he has synthesised nearly all the products of 



