234 



BACTERIAL ORIGIN OF GUMS OF ARABIN GROUP, 



formed upon the branch in one of the flasks. This was extracted 

 and smeared over the surface of a levulose-asparagine-tannin-agar 

 plate. A slime developed and a portion (large loopful) was used 

 for smearing another plate. The slime that grew was "plated" 

 upon saccharose-potato-agar, and two of the colonies that 

 developed were grown upon the same medium. These growths 

 were smeared over plates of media containing various sugars, and 

 at the same time the cultures were tested upon glucose-gelatine 

 for purity and for their identification. The cultures were pure; 

 one of them was Bact. metarahinum, and the other Bact. acacice. 

 Upon the experimental media the former produced a dry leathery 

 slime that could not be removed from the plates. The indications, 

 however, were that levulose was the best carbohydrate and 

 saccharose the next. Bact. acacice grew as a slime which was 

 decidedly more viscous or ropy than were the races after much 

 subculture 

 table : — 



The weights of slime are given in the following 



Slime- Production by a freshly isolated Race of Bact. acacu 



The yields are not so great as had been obtained with the older 

 bacterium. The new organism was probably a weaker race. It 

 did not grow so strongly upon artificial media and was of a paler 

 colour. The older race was of a deep yellow colour on saccharose- 

 potato-agar; the new race was white, with a buff tinge. 



The utilisation of saccharose and maltose. — The experiments 

 with the or^ranism and various sugars have shown that the gum 



Sugars 2, asparagine 0*1, tannin 0-1, potassium citrate 0-1, agar 2, water 100. 



