550 BACTERIAL ORIGIN OF GUMS OF ARABIN GROUP, 



The acids produced during the growth of the organism in 

 saccharose solutions are therefore succinic, lauric, butyric, acetic 

 and formic, the relative proportions being in that order. Besides 

 these acids, ethyl alcohol and carbon dioxide are formed. 



The organism did not produce characteristic growths upon 

 the various media. The most distinctive characters were perhaps 

 the production of a gummy slime on saccharose-potato-agar, and 

 of a pronounced viscosity in fluid media containing certain 

 sugars, etc., and chalk. As pararabin has never before been 

 shown to result from bacterial activity, it is probable that the 

 organism is new,* and I have accordingly named it Jjacteriiim 

 pararabiniim, n.sp. (Bacillvs pararobhms, n.sp., by Migula's 

 nomenclature). 



Bacterium pararabinum, n.sp. 



Shape, etc. — The organism appears as an actively motile, short 

 thick rod with rounded ends. It tends to form long rods, chains, 

 and threads in old cultures. The young cells, as taken from a 

 24 hours' agar culture, measure 0-6-0-7 : 0-8-1/i. The flagella may 

 be single and terminal, or numerous and peritrichous: up to seven 

 have been observed upon one cell. The rods colour readily with 

 the ordinary stains, and are decolorised by the Gram method. 

 Spores were not observed. 



Temperature, etc. — The growth temperatures have been noted 

 on page 544. The bacterium is aerobic; no growth occurred under 

 the mica plate. 



Nutrient agar plate. — At 30° the colonies are circular, raised 

 translucent-white and gummy. Microscopically they are rounded 

 and finely granular, with irregular curved structures scattered 

 here and there. The deep colonies are oval, rounded or 

 lenticular, and coarsely granular. 



Glucose-gelatine plate. — In two days at 22° the colonies were 

 white, rounded, raised and gum-like, although they did not draw 



* Bad. gelatinosum betce, Fritz Glaser, a dextran bacterium, appears to 

 be the most closely related slime-forming organism. 



