31 



THE GUMMOSIS OF THE SUGAR-CANE. 



{Bad. vascularum^ Cobb). 



By R. Greig Smith, M.Sc, Macleay Bacteriologist to the 



SociETy. 



(Plates iv.-v.) 



Gummosis is a disease pretty widely distributed among plants,, 

 and is recognised by an unhealthy appearance of the plant as a 

 whole, by the leaves dying or rotting, and especially by the 

 presence of a yellowish gummy matter in the vessels. On cutting-^ 

 across the vessels of a badly diseased plant, such as the sugar- 

 cane, small yellow viscid drops of gum quickly gather on the cut 

 ends of the vascular bundles. In slightly diseased plants the 

 microscope may be necessary to demonstrate the gum plugging-^ 

 the vessels. The disease has been specially noted in the sugar- 

 cane, the sugar-beet and the vine chiefly on account of the 

 economic importance of these plants, but it is not unknown 

 among other members of the vegetable kingdom, as for example 

 the fig, olive, mulberry, potato, carrot, and tomato. 



The c-'ummosis of the vine has been ascribed to the activity of 

 a bacterium by Prillieux et Delacroix,"^ but Mangin,t and also 

 Ratha}',! consider that the formation of gum in the vessels by 

 bacteria is very problematical. Indeed, Mangin goes further and 

 says that the bacteria live upon the gum. 



* Prillieux et Delacroix, Cent. f. Bakt., 2 Abt., i., 300, Eef. 



tMangin, op. rit. and also ibid. 11., 621, Ref. 



JRathay, ibid, ii., 620, Ref. 



