534 THE PATHOGENIC BACTERIA. 



Bacterial Disease of the Mulberry.^ 



Cavities containing bacteria have been found in brown spots 

 on diseased leaves and twigs of the mulberry. A form 

 "Bacterium mori" was isolated and found to reproduce the 

 disease when used to infect healthy leaves. I have myself 

 observed, in the arboretum of the forest experimental station 

 at Munich, most of the new twigs of an old mulberry tree 

 beset with brown spots over the whole green tissue. The 

 leaves on such twigs were not spotted, but died off prematurely. 

 The spots indicated cavities filled with bacteria and a slimy 

 substance. 



" Mai nero " of the Vine. 



This name is given to certain diseases of the vine, the cause 

 of which has never been satisfactorily explained. Baccarini^ 

 succeeded in obtaining all the symptoms of the disease after 

 infecting healthy twigs by grafting on diseased pieces. Prillieux 

 and Delacroix^ describe a similar disease prevalent in Tunis 

 and throughout France, with the name " Aubernage." The 

 wood when attacked exhibits black points which rapidly 

 enlarge and coalesce, causing it to decay. All diseased elements 

 were found to contain a brown gummy substance in which a 

 form of Zep^o^ArM-bacterium swarmed. Inoculation of healthy 

 vines produced the disease in the following year. 



Certain diseases of the grape have also been ascribed to 

 bacterial action, and investigations are at present in progress. 



Sorghum Blight. 



A disease of species of Sorghum has been long known in 

 America, especially on S. saccharatum, one of the sources of 

 sugar. The symptoms are red or black spotting of the leaves 

 and other parts of the plant. The disease may even be severe 

 enough to cause death of the host-plants. Burrill in 1886 

 found a bacterial form present in the spots, and named it 

 Bacillus sorghi. Kellermann and Swingle* obtained pure cultures, 



'Boyer and Lambert, "Deux maladies du Mflrier," Compt. rend., cxvii., 1893. 

 ^ Malpighia, vi. ; also Bullet, d. Sloe, botan. Ital., 1894. 

 ^"La gommose baoillaire d. Vignes," Comptes rend., cxviil., 1S94. 

 ^Report of botanical department of Kansas State Aijric. Colte(je, 1889. 



