172 Bacteriolog^ie. 



Smith, R. Greig, Further Remarks upon the Mechanism ot 

 Agglutination. (Abstr. Proc. Linn. Soc. N. S. Wales 1902.) 



Recent writers upon this subject, while agreeing that the process 

 is a Chemical one, do not appear to understand the function of salts 

 in the mechanism of chemical precipitation, coagulation, flocculation 

 er agglutination. In former papers the author has shown the röle of 

 salts in flocculation and chemical precipitation, and the identity of 

 agglutination with precipitation. Agglutination is now explained in 

 extenso by the hydrate theory of Solution. Harri sson has inferred 

 that the ägglutinable substance is located on the outer membranes 

 of the microbic cell because he obtained no agglutination after the 

 bacteria had been treated with pyocyanase and washed with water. 

 The author points out that the removal of the membrane enabled 

 the ägglutinable substance to readily diffuse into the wash water 

 from the inferior of the cell. Smith. 



Smith, R. Greig, The Bacterial Origin of the Gums of 

 the Ära bin Group. (Abstr. Proc. Linn.^Soc. N. S. Wales. 1902.) 



I. The soluble fArabinJ Wattle Gums. 



A bacterium {Bact. acacioe , n. sp.) was found in pure culture in 

 the tissues of Acacia hmervata from which gum was exuding. In the 

 laboratory it produced a gum which behaved to reagents, gave the 

 same oxidation products and contained the same constituents, viz., 

 arabinan and galactan, as the natural gum. This soluble gum, and 

 probably all others of a similar nature, are therefore of bacterial 

 origin, a circumstance which had been suggested by the irregulär 

 distribution of gum-bearing trees. 



II. The insoluhle (Metarahin) Wattle Gums. 



In Company with Bact. acaci(s, a bacterium (Bact. metarabinum , 

 n.sp.) was separated from the- bast of Acacia penninervis affected 

 Avith gumming. In artificial culture it formed a gum which swelled 

 with \vater like the metarabin gums. The gum gives the same 

 reactions and contains the same arabinan-galactan complex as the 

 natural gum. The metarabin is, therefore , the product of this organism. 



Smith. 



Smith, R. Greig, The Bacterial Origin of the Gums of the 

 Arabin Group. (Abstr. Proc. Linn. Soc. N. S. Wales. 1903). 



III. The Acids produced during the Growth of Bact. acacice and 

 Bact. metarabinum in Saccharose media. 



These bacteria yielded the same acids in approximately the 

 same proportions. They consisted chiefly of lactic and acetic, with 

 smaller quantities of succinic, formic and lauric, and traces of oxalic. 

 Ethyl alcohol is lormed and carbon dioxide is evolved. 



IV. The Gum-ßux of the Vine. 



This is not the gummosis (mal nero) of the vine, but an exuda- 

 tion of gum from pruned branches. Bact. acacics and Bact. metara- 

 binum were isolated. The weathered natural gum consisted of 



