34 THE GUMMOSIS OF THE SUGAR-CAN K, 



identity of the organism would be placed beyond all doubt. The 

 question, then, as to the gum being a pathogenic secretion of the 

 plant itself would be answered conclusively in the negative. 



The Isolation of the Organism. 



To facilitate the investigation the Colonial Sugar Refining Co. 

 offered me a portion of their small supply of cane-gum which had 

 been collected some years ago. Furthermore, one of their officers, 

 Mr. Morison, inoculated tubes of media in the cane fields with 

 gum exuded from diseased canes. As, however, I received several 

 specimens of gummed cane, the tube cultures w^hich did not con- 

 tain the desired organism need not be further noticed. The 

 specimens of diseased cane were the variety known as Rappoe, 

 and, on being cut across, small yellow viscid drops exuded from 

 the ends of the cut vessels. By using a lens of low power ( x 10) 

 minute portions from the centre of exuded drops of gum wei-e 

 abstracted and inoculated into various media, which were placed 

 under different conditions of culture. It need scarcely be said 

 that the cane was cut and the infections made with the usual 

 precautions as regards sterilising the outer surface of the cane, 

 knives, etc. 



Under anaerobic conditions there was no growth either in tluid 

 or on solid media. On slices of cane and in acid fluids such as 

 wort and cane-juice no bacteria developed. In other neutral 

 fluids the bacteria grew scantily. On agar and gelatine in the 

 presence of cane or fruit sugar bacteria grew slowly at tempera- 

 tures of 30° C. and under; at 37° and over no growth coidd be 

 obtained under any condition whatsoe^'er. What appeared to 

 be the most suitable medium for the grow^th of the gum bacteria 

 was neutral cane-juice gelatine. The next best media were 

 ordinary glucose gelatine and slices of potato. From the growth 

 on cane gelatine a bacterium was separated in the pure state by 

 repeated cultivation upon plates of cane gelatine, and its cultural 

 characters were studied upon other media. The appearances of 

 the cultures are given at the end of this paper, and they will 

 serve to identify the organism. 



