LECTURE XI. 



2, the decomposition of glucosides ; 



Amygdalin. Oil of Bitter Almonds. Prussic acid. Glucose. 



C ao H a7 NO 11 + 2H 2 O = C 7 H 6 O +HCN + 2 (C 6 H 12 O 6 ) : 



3, the conversion of cane-sugar into glucose ; 



Cane-sugar. Dextrose. Laevulose. 



QjHfflOn + H 2 = C 6 H 12 O 6 + C 6 H 12 O 6 : 



it -was long thought that the product was a substance termed "inverted 

 cane-sugar " ; Dubrunfaut, however, pointed out that it is a mixture of 

 dextrose and Isevulose ; it rotates the plane of polarization to the left on 

 account of the more powerful optical properties of the lasvulose. 



4, the decomposition of fats (glycerides) ; 



Olei'n. Oleic acid. Glycerin. 



C 67 H 104 6 + 3 H 2 = 3 C 18 H 34 2 + C 3 H 8 O 3 . 



No equation can be given of the conversion of insoluble proteid into 

 peptone for the formula of proteid is not known. 



For the same reason no equation can be given of the production of 

 amides from proteid by ferment-action. It appears that in pancreatic 

 digestion the first step is the formation of peptone, and that the peptone 

 then undergoes decomposition ; leucin and tyrosin are the principal 

 products, and aspartic acid, bodies belonging to the xanthin group an 

 aromatic acid, and certain little-known substances, are also formed. 



The action of the ferments of plants is- considerably 

 affected by external conditions. For instance, it was pointed 

 out above that the action of a diastatic ferment on starch is 

 not the same at different temperatures, and it has been found 

 that there are limits of temperature above and below which 

 the action does not take place at all. This is doubtless true 

 of the action of all ferments. Again, Baranetzky has ob- 

 served that the diastatic ferments are only active when the 

 liquid in which they are dissolved has a distinct, but not too 

 strong, acid reaction, a condition which is also essential in 

 the case of the peptic ferments. Further, it appears that 

 the presence of free oxygen is of importance in the case 

 of the diastatic ferments : thus Wortmann observed that 

 Bacteria do not convert starch into sugar in the absence 

 of free oxygen, and Baranetzky found that a solution of 

 freshly prepared extract (of leaves of Melianthus major, also 

 of potato-tubers) was inactive, whereas after standing for 

 a few days its action upon starch was rapid. But it is 

 probable that these conditions affect rather the formation 



