KErOET OF OHEMiCAL LAliOUATOEY 
449 
Tlie Subakh gum is the only one to contain any mineral matter except calcium, 
magnesium and potassium. 
From the analogy of Hashab and Talli gum, there is every reason to expect that 
specimens of Sunt and other gums from different localities and collected at different 
seasons would show optical activity and j)roportious of arabinose to hexoses practically 
the same as those mentioned above, a polarimetrical examination being the most 
convenient. It should be stated that all the figures for rotation in this paper refer 
to tlie sodium flame. 
The Bacteeial Okioin of Gum 
*v- 
>* 
V { 
,>.l 
<. 
/ 
Under the above title, Greig Smith^ first published an account of researches conducted 
by him on the gum from Acacia penninervis, from twigs of which lie isolated two kinds of 
bacteria. The prevalent type, which he calls liact. acacia, produced, when grown on 
artificial media, a slime from which a gum of the arabin-galactan class w’as obtained 
by suitable treatment. This work has 
been described in great detail in 
subsequent papers by Greig Smith, who 
found that “ gum-flux ” in other species 
of trees could be accounted for by 
bacterial action also, and his results 
appear conclusive. Euhland,- however, 
questions Greig Smith’s view of the 
bacterial origin of gum, though he found 
that Bacilhis spongiosits, isolated from 
diseased cherry trees, produced, when 
grown in artificial media, a slime from 
which a gum was isolated. This gum 
he found only to yield arabinose on 
hydrolysis, while the gum from cherry 
trees inoculated with the bacillus 
yielded a mixture of arabinose and 
galactose. In a later paper, Ruhland^ 
discusses the formation of gum by the 
action of the oxygen of the air on a 
substance in the sap which might be called a reduced “ gum-base. 
Zimmermann,'* working with Acacia Jecnrren.t, connects gum formation in this case 
with the borings of Ambrosia beetles, but he gives no account of what the method of 
gum formation is. He mentions one interesting point, however namely, that all the 
artificial methods of gum production which have been described involve some injury to 
the tree. This, it will be readily seen, affords the bacteria more easy access to the tree, 
and they might simply be carried in mechanically. 
I have endeavoured to confirm Greig Smith’s work in the case of Ilashab gum; some 
branches, from which gum was exuding, being kindly sent from Kordofan by Mr. Tippetts, 
•lunior Inspector at Taiara. After sterilising the exterior of small pieces of these branches 
‘ Broc. Linn. Soc. nfN.S. IF., 1902, Part III., September 24th. 
Jler. deatsch. bntini. (hs., 1900, XXIV., 393. 
“ Ibid., 1907, XXV., .302. 
Ventralbl. f. Bakt. etc. ; II. Abt., H<1. XX., p. 710. 
Ft*. 218.—BiicWni 
Liiffiey^s blue 
,ni iROlatod from gum bearing branch of /Uaiia vcrek. 
grown on saccharo»e potato agar 
X 1000 diam. 
DD 
Gum 
bacilli 
Gum and 
beetles 
