824 THE ROLE OF NITROGEN', ETC., I., 



protein-hydrolysis. By noting the common antecedents of the 

 synthetic products he concludes that both hydrocyanic acid and 

 benzaldehyde, among others, may be the earliest products formed 

 in the synthesis of protein. It must be remembered that those 

 reactions, which are so difficult to perform in vitro, take place 

 with ease when catalysed by enzjmies; for instance, the synthesis 

 of amygdalin was accomplished by Emmerling(84) from glucose 

 and one of the cyan-alcohols with the maltase of yeast, and 

 salicin(85) was synthesised with emulsin. 



All these are evidence that the cyanogenetic glucosides are not 

 end-products but that they may function as reserve-material, and 

 by their slow hydrolysis supply the active substances which are 

 known to make the precursors of protein. When the hydro- 

 cyanic acid is liberated from these stores by enzyme-action, and 

 is not consumed just as fast in the synthetic process, then it must 

 accumulate, and we are enabled to detect its presence. Fre- 

 quently it has been noticed that l^drocyanic acid is detected 

 only in very young plants, and, as they grow older, that it gradu- 

 ally disappears. We have instances of the result of this in the 

 poisoning of cattle when young green fodder, especially legumes, 

 has been eaten. 



A number of different nitrogenous glucosides have been isolated 

 from various plants, but beyond the fact that the simple hydro- 

 lytic products are hydrocyanic acid and sugar, very little is 

 known of their constitution. Among them may be mentioned 

 vicianin(86) discovered by Bertrand in Vicia angitstifolia, sinalbin 

 and sinigrin of mustard-seeds, solanin in the species of Solanum, 

 and indican from Indigofera. 



The Bio-Chemistry of Germination. 



When the necessary conditions of moisture and temperature 

 exist, certain physiological and chemical changes are initiated in 

 the seed. The hypnotic stage has ended, and a sudden activation 

 of the zymogens or pro-ferments takes place, by which very active 

 enzymes are rapidly formed. These bring about the hydrolytic 

 changes in the seed-constituents, the insoluble stored material 



