866 THE BACTERIAL ORIGIN OF xAIACROZAMIA GUM, 



monly occurring sugar, the investigation was deferred for about 

 six months. 



During this interval the examination of the gum from Hakea 

 saligna had been undertaken, and the products of hydrolysis had 

 been found to consist of substances that reduced Fehling's solu- 

 tion and that gave osazones which were not those of the sugars 

 ordinarily obtained from the vegetable gums. Hakea gum was, 

 therefore, not peculiar in yielding hydrolytic products which 

 reduced Fehling's solution and at the same time gave no well- 

 known osazone. Having gained this knowledge, I resumed the 

 research. 



The bacterial gum was subjected to investigation. The slime 

 was grown upon the levulose medium which had been found so 

 useful, and from it the gum was prepared in the usual manner. 

 Upon being tested with the reagents, it was found to have altered 

 materially. During the six months that the organism had been 

 under cultivation in the laboratory, the physiological activit}^, as 

 represented by the reactions of the typical product of the microbe, 

 had changed. The gum now gave the reactions of arabin. For- 

 merly, barium hydrate had produced a precipitate, and ferric 

 chloride gave no reaction, wdiile now the former gave no precipi- 

 tate and the latter produced a brown clot. This was rather 

 unexpected, but was a point to be taken into consideration when 

 comparing the reactions of the natural gum with those of the 

 bacterial product. The slight divergence of the bacterial gum, 

 formed by the organism soon after its isolation from the plant, 

 becomes of little moment, and the only wonder is that the 

 reactions should have agreed so closely. This emphasises another 

 point, which is that such tests ought to be made as soon after 

 the isolation of the organism as is possible if they are to be of 

 any value. 



The gum, after being freed from sugars by repeated precipita- 

 tion of the mucilage with alcohol, was hydrolysed by being boiled 

 with 5 % sulphuric acid for six hours. After neutralisation with 

 barium carbonate, the solution showed the presence of reducing 

 sugars and the absence of unaltered gum. The osazones, ob- 



