136 



THE POSSIBLE RELATIONSHIP BETWEEN BACTERIA 

 AND THE GUM OF HAKEA SALIGNA. 



(Bac. pseudarabinus a., n.sp.) 



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



Society. 



Specimens of gum that were picked from Hakea saligna ap- 

 peared as transparent, colourless, rounded and conical masses as 

 well as clusters of conical drops (tears). Other fragments were 

 brownish-yellow and blackish. They were easily cut with a 

 knife, showing that they had a tough and gelatinous but not a 

 brittle consistency. Some of the conical masses measured about 

 4 cm. in circumference and 1 cm. high, the base being attached 

 to the bark of the tree through punctures from which the gum had 

 exuded. 



The gums of species of Hakea other than Hakea saligna have 

 been examined by Maiden,"^ who found that they consisted of 

 arabin (5-16%) and pararabin (63-69 %), together with moisture 

 and ash. He also notesf the presence of a jelly at the roots of 

 certain Hakeas, but that was probably the undried gum. 



The gum which I received when placed in a small quantity of 

 water swelled in it, forming a thick paste of the lumpy consistency 

 •of fruit jam. With much water a homogeneous paste was formed 

 in a day or two. The water made no differentiation between 

 parts of the gum; it appeared to be a single substance, not a 

 mixture ot two constituents with differing solubilities. The 

 viscosity of the gum appeared to be midway between arabin and 

 metarabin. 



* Proc. Roy. Soc. S. Australia, 1889, 54. 

 + Proc. Roy. Soc. N. S. Wales, 1901, 161. 



