BACTERIA 521 



coloured patches appear on the bark ; these patches eventu- 

 ally crack, and as the wound expands it becomes surrounded 

 by an irregular, rugged, raised border; the canker in some 

 instances measures an inch in length. The leaves are also 

 attacked, small brown patches appear mostly on the upper 

 side, the tissue becomes thickened at these places, and finally 

 breaks open in an irregular manner. The general character- 

 istics of the disease resemble those described under the Ash. 

 The rod-shaped organisms measure about 2 Xo'3 fi. 



Lindau, Zeit. Pflanzenkr., 4, p. 1 (1894). 



Sugar-beet gummosis. Busse has described a disease of 

 sugar-beet caused by a bacterium, in which the flesh situated 

 between the vascular bundles of the root is converted into 

 a gum-like substance. The vascular bundles also become 

 blackened. 



The bacterium consists of short rods with rounded ends, 

 175-2 xo'9/x, sometimes almost egg-shaped. Diphlobacteria 

 are abundant ; very motile. 



Busse, W., Zeitschr. Pflanzenkr., 7, pp. 65 and 149 (1897). 



Sesamum leaf blotch. Malkoff describes a bacterial disease 

 of Sesamum orietitale from Bulgaria. Dark-brown spots appear 

 on the leaves, which soon become blackish and shrivel. A 

 thick slimy mass exudes from the diseased spots, which, when 

 introduced into healthy plants, produced the disease. Two 

 bacteria were isolated, but not studied. 



Malkoff, K., Centralb.f. Bakt. Abt, 2, vol. ii. (1903). 



Vine gummosis. A disease, known in Italy as 'mal nero, 

 has for a long time been known as very destructive to vines. 

 It has also appeared in certain districts in France. Diseased 

 vines are stunted in growth, the young branches do not attain 

 their full development, and the leaves are deformed and often 

 show deep incisions. If the stem is cut across, black points 

 are seen to be present in the wood. These spots increase in 

 size and run into each other, forming large patches. At the 

 end the parts attacked become brown. The injury starts in 

 the stem and passes downwards into the root. At the same 

 time radial fissures appear in the bark. Structures resembling 

 lenticels are usually produced in abundance on the diseased 

 portions of the stem. The wood underneath the diseased 

 portions of bark undergoes great changes, which results in 



