THE METABOLISM OF PLANTS. 189 



ferments are formed by the protoplasm and appear to resemble 

 proteids in their ultimate chemical composition, but we do not 

 know what is the nature of the peculiarity of their chemical 

 structure upon which their characteristic properties depend. 



The following are the analyses of certain of these ferments : 



Emulsin Papai'n Diastase 



(Schmidt). (Wurtz and Bouchut). Zulkowsky). 



C 4876 42-20 47-57 



H 7*13 6'6o 6'49 



N 14-16 i2'22 5-14 



S 1-25 ) 



O 28-70 (and S?) 26-08 J 37 ' 64 



Ash 12-90 3-16 



lOO'OO lOO'OO lOO'OO 



Loew has come to the conclusion, by the analysis of ferments, that 

 they are proteids allied to the peptones. 



The unorganised ferments may be classified, according to 

 our present knowledge in the following four groups, the 

 classification depending upon the nature of their action : 



(1) Ferments which convert starch into sugar; the first 

 of these to be discovered was called diastase and was found 

 in malt; we may speak of these ferments generally as dia- 

 static ferments. They are very widely distributed in plants ; 

 they have been found in germinating seeds (Persoz and 

 Payen, von Gorup-Besanez), in leaves, shoots, etc. (Kossman, 

 Krauch); Wortmann has recently found reason to believe 

 that Bacteria convert starch into sugar by means of a dia- 

 static ferment which they excrete ; in fact it seems probable 

 from the researches of Baranetzky that a ferment of this kind 

 is present in all living plant-cells. 



(2) Ferments which decompose glucosides with produc- 

 tion of sugar : the best-known members of this group are 

 emulsin or synaptase found in the Bitter Almond ; myrosin 

 in the seed of the Black Mustard ; erythrozym in the root 

 of the Madder. 



It is doubtful whether or not these ferments are also 

 capable of converting starch into sugar. According to 

 Schmidt, emulsin does not possess this property, its action 



