PRESIDENT S ADDRESS. 



a bacterium, showed that it produced pararabin. Thus the origin 

 of the chief members of the arabin group of gums has been traced 

 to certain organisms which convert the sap of the host plant into 



sum. 



Although the chief agents in gum-formation are these three 

 bacteria, yet others may be present in the plant tissues, and 

 contribute a portion of the exudate. This was found to be the 

 case with Bad. persicce, which produces a gum allied to the 

 members of the arabin group. 



Occasionally a yeast-like mould, Dematium pullulans, is found 

 in the tissues of gummed fruits, and as it has been credited with 

 being the cause of certain cases of gum-flux, its investigation was 

 undertaken. It was, however, found to produce a pararabin 

 gum, and could not, therefore, be responsible for the arabin and 

 metarabin gums of the fruit. It had been previously shown that 

 an organism, Bad. sacchari, which normally inhabits the tissues 

 of the sugar-cane, was capable of producing a slime. This was 

 investigated, and found to consist essentially of a galactan gum. 

 This work, which had been done by the Society's Bacteriologist, 

 has thus greatly advanced our knowledge concerning the forma- 

 tion of the chief vegetable gums; and not only has it been of 

 scientific value, but it has also been of considerable economic 

 importance. The world's supply of gum acacia can now be 

 increased, as well as improved, by the infection of suitable trees 

 with a selected bacterium. 



During the year two students received full courses of laboratory 

 instruction. 



In August last we were called upon to mourn the death of 

 Lady Macleay, after a brief illness. This sad event closed a most 

 interesting chapter of colonial family-histor}^ Her grandfather. 

 Sir Richard Bourke, K.C.B., was one of the most enlightened and 

 popular of Australian Governors. Her father, the late Sir Edward 

 Deas Thomson, C.B., K.C.M.G , is still remembered by some of 

 us as the courtly Chancellor of the University of Sydney. Sir 

 Edward came out to New South Wales in 1828, about three years 

 later than Mr. Alexander Macleay, whom he succeeded, as Colonial 



