BY R. GREIG SMITH. 235 



is formed from asparagine and levulose. The organism does not 

 secrete invertase, and as it can be made to gain the power of 

 utilising saccharose it is evident that this sugar must be used as 

 such, and not as either or both of the products of hydrolysis. 

 Furthermore, the yield of slime from saccharose when the 

 bacterium is thoroughly accustomed to this sugar is very much 

 greater than what is obtained from a mixture of dextrose and 

 levulose. Maltose must also be utilised as such, for its product 

 of hydrolysis, dextrose, is incapable of assisting gum-formation. 



The gum is not derived frovi cellulose. — The production of the 

 gum from levulose has a direct bearing upon certain hypotheses 

 regarding the origin from cellulose. 



Cellulose is a broad term and the statement is on that account 

 sweeping. Under the term may be included substances of such 

 diverse characters and composition as resistant cellulose, the 

 hydrocelluloses, hemicelluloses, the pectins and the oxycelluloses."*^ 

 The hydrolysed products of these bodies consist of one or more 

 of the following sugars : — dextrose, levulose, mannose, galactose, 

 arabinose, xylose, the furfiiroids of Cross, Bevan and Smith, and 

 possibly others. 



The production of gum by the bacterium from any of these 

 celluloses would assume, firstly, that the organism secreted a 

 cellulose-dissolving enzyme, and secondly, that the products of 

 zymolysis were capable of being utilised. In the first place there 

 is no evidence to show that the organism does secrete such an 

 enzyme. The presence in plants of a gum-ferment capable of 

 converting cellulose into gum has been claimed by Weisner, but 

 this has been contradicted by Reinitzer, who regards it as a simple 

 diastase. 



In the second place, many of the celluloses give dextrose or 

 galactose only upon hydrolysis, and such would be useless as gum- 

 producers. Levulose is rarely produced, but when yielded by 

 certain hemicelluloses | the accompanying dextrose would prevent 



* Tollens, Abstract in Journ. Soc. Chem. Ind. 20, 740. 

 t Oppenheimer, Ferments and their Actions, 189. 

 X Schulze und Castoro, Biochem. Cent. i. 785. 



