40 MICROBES, FERMENTS, AND MOULDS. 



by a fungus, but by a degeneration which is either 

 spontaneous or, as Pirotta and Cugini suggest, the 

 work of bacteria, and which consists in the trans- 

 formation of the cellulose and starch of the plant 

 into dextrine, as Comes asserts, or, according to Pirotta, 

 into tannin. 



This disease appears in three stages : (1) a simple 

 discolouration of the sap, which assumes a tawny 

 black shade without checking vegetation ; (2) a begin- 

 ning of necrosis, which renders the plant unhealthy ; 

 (3) a complete necrosis, which affects the woody parts 

 and arrests the growth of the plant. 



This disease is contagious, which leads us to 

 believe that if it is not produced by a fungus, it is 

 at any rate due to the development of a bacterium 

 that is, of a microbe. 



The remedy indicated by Italian naturalists con- 

 sists in the application of salts of potassium, which 

 may be extracted at small cost from the ashes of the 

 vine branches which are burnt upon the spot. 



JRoesleria Tiypogea, or Rot. This parasitic fungus is 

 found on the vine-roots, and has been recently studied 

 by Prillieux. The vine affected by this parasite 

 languishes for some years and then dies. The evil 

 spreads by means of the roots to adjoining stocks, 

 and the parts affected spread like the patches formed 

 by the phylloxera. The roots rot away. This disease 

 has been widely spread in Haute Marne. 



This small fungus is distinct from one which bears 



