32 THE GUMMOSIS OF THE SUGAR-CANE, 



The gummosis of the sugar-beet has been investigated by many. 

 Among others, Arthur and Golden separated a bacterium which, 

 when inoculated into sound beets, produced the disease in some 

 cases. Busse"^ also investigated the disease, and concluded from 

 his own experiments and from those of others that there is a group 

 of bacteria which cause the gummosis of the beet. He experi- 

 mented upon sound beets with pure cultures, and found that after 

 a period of growth the infected roots had developed a greater or 

 less gummosis. The bacteria that are claimed as being the 

 exciting cause of gummosis of the beet are all capsulated, non- 

 sporulating organisms, and it would appear that the gum is the 

 capsular envelope. 



The Gummosis of the Cane. 



The bacteriology of the gumming of the sugar-cane has been 

 investigated by Cobb,t who invariably found microbes in the gum 

 of diseased stalks. He inoculated the gum into tubes of agar and 

 gelatine and obtained bacterial growths. The cultural characters 

 of the organism are described as follows: — "Cultures on agar- 

 agar gave at first roundish colonies on the surface having to the 

 unaided eye no structure, either radiated or concentric. In the 

 course of a few weeks the yellowish white and somewhat opal- 

 escent growth had extended several inches along the edge of the 

 tube on the surface of the agar-agar and between the tube and 

 the agar-agar without causing any liquefaction. On gelatine the 

 growth was much slower, and remained circular and almost im- 

 perceptibly concentric. Its colour, itc, were as on agar-agar." 

 The italics are in the original. 



It is unfortunate that the only information regarding the 

 growth characters which enables the organism to be identified is 

 so limited. The description would apply to at least eleven 



described non-liquefying species of bacteria. The characters, 



f 



*Busse, Cent. f. Bakt., 2 Abt., ill., 680, Kef. 

 t Cobb, Agric. Gazette of N.S. Wales, 1893. 



