864 



THE BACTERIAL ORIGIN OF MACROZAMIA GUM, 



gelatine which was incubated at 30° for five hours before pre- 

 paring a plate. On the gelatine there developed colonies of Bac. 

 levaniforynans. Another portion of the same part of the plant 

 was incubated in glucose-gelatine for two days. The molten 

 medium was then smeared over plates of levulose-asparagine- 

 tannin-agar, upon which a slime formed. From the slime an 

 organism was isolated. It grew as white, nipple-shaped colonies 

 that gave promise of containing gum. 



A quantity of the slime formed by the bacterium was obtained 

 by growing the organism upon levulose-asparagine-tannin-agar, 

 and from the slime a gum was prepared by heating an aqueous 

 suspension of the partially purified slime in the autoclave. A 

 strong solution, that is a mucilage, of this gum was tested with 

 the usual reagents, and at the same time there was also tested a 

 mucilage of the natural gum which had been subjected to a 

 similar treatment in the autoclave in order to bring it into a 

 soluble condition. The results are given ia the following table. 



The Reactions of the Natural and the Bacterial Gums. 



I Macrozamia gum. 



Basic lead acetate 

 Neutral lead acetate 

 Barium hydrate ... 

 Fehling's solution 

 Ferric chloride ... 

 Copi^er sulphate .. 

 Alcohol 



thickened. 



t 

 thickened. 

 

 

 t 



Bacterial gum. 



■' t "=:a clot or a precipitate; 

 " 0" = no reaction. 



If we ignore the thickening of the natural gum by the two 

 reagents, we see that the bacterial gum has the same reactions 

 as the natural gum. On this account there is the probabilit}^ 

 that the organism caused the formation of the natural gum, but 

 before the two can be bracketed together as the cause and the 

 effect, a further examination of the gum was necessary. I do 

 not place much value upon the chemical reactions of the gum- 



