383 



THE BACTERIAL ORIGIN OF THE GUMS OF THE 

 ARABIN GROUP. 



By R. Greig Smith, M.Sc, Macleay Bacteriologist to the 



Society. 



I. — The Soluble (Arabin) Wattle Gums. 

 {Bacterium acacice, n.sp.) 



While working upon the gums and slimes produced by some 

 bacteria, it seemed to be exceedingly probable that a few of the 

 gums which occur naturally or are supposed to be formed during 

 a pathological condition of the plant, might have a bacterial 

 origin. Like the mucilages, gums and slimes formed in or on the 

 higher plants, the bacterial slimes are of a varied nature. For 

 example, dextran may be considered as a dextrose anhydride, 

 levan as a levulose anhj^dride, the gums of Schardinger and 

 Adametz as galactose anhydrides ; the bacterium of Marshall 

 Ward and Reynolds Green produces a hemi-cellulose, and Brown's 

 Bad. xylinuni has a cellulose en\ elope. The bacterium which I 

 separated from the sugar-cane forms a pentosan slime. 



Perhaps the most valuable of the vegetable gums are those of 

 the arabinan-galactan class such as gum arabic and wattle gum; 

 and when one studies the distribution of this kind, it appears to be 

 quite within the bounds of possibility that bacteria have more to 

 do with its formation than would at first appear. Indeed it is 

 extremely probable. In the first place, the gum exudes from 

 cracks* or from punctures or wounds made by insects The 



* " Wattle gum exudes chiefly during the summer season from fissures 

 and accidental injuries to the bark. . After careful observation I have formed 

 the opinion that, as a very general rule, it is a pathological product. I came 

 to this conclusion long before I was aware of Trecul's observations that 

 Acacias and the Kosacese yield their gums most abundantly when sickly and 

 in an abnormal state caused by a fulness of sap in the young tissues." — 

 Maiden, Pharm. Jour. [3] xx. (1890), 869. 



