863 



TaE BACTERIAL ORIGIN OF MACROZAMIA GUM. 



{Bacillus macrozami^e, n.sp.) 



By R. Grkig Smith, D.Sc, Macleay Bacteriologist to the 



Society. 



The fruit of a Macrozamia spiralis, iu the Societ3^'s garden, was 

 found to be exuding a transparent, colourless and gelatinous gum. 

 The transparent globules of the dried gum swelled with water 

 but did not dissolve, and in this respect resembled the insoluble 

 gums of the members of the Bosacece and Acacice. A film pre- 

 paration of the fresh gum showed, here and there, thin, short, 

 rod-shaped bacteria and occasionally a suhtilis-like cell. The 

 swollen gum w^as soluble in hot dilute acid and alkali, but it dis- 

 solved much more readily in the latter than in the former. 



Maiden published a paper* upon Macrozamia gum, and in it 

 he showed that the gum consisted of metarabin (72-77 %), with 

 .a trace of arabin (1 %), besides sugar (1 %), water and ash. 



Plates of glucose-gelatine media, that had been infected with 

 the fresh gum, produced in five days small, punctiform colonies, 

 which slowly increased in size, and appeared as small hemi- 

 spherical drops of white flour-paste. Microscopically they con- 

 sisted of tine granules arranged uniformly. Upon saccharose- 

 potato-agar, the growth consisted of a white gravitating slime. The 

 gum, obtained from the slime, gelatinised upon cooling, and was 

 on this account somewhat similar to the natural gum, but further 

 research showed that it was absolutely different and that the 

 -organism was Rhizohium leguminosarum. This micro-organism 

 will be considered in another paper. 



A portion of the stalk, attached to the fruit, was cut off, and with 

 the usual precautions a part was inserted into molten glucose- 



• Chem. and Druggist of Australasia, Jan., Feb., 1S90. 



