532 THE PATHOGENIC BACTERIA. 



diseased branches, and is one of those forms which does not 

 liquefy gelatine. One characteristic reaction is, that as destruc- 

 tion of the tree-rind proceeds, fermentation takes place with 

 production of carbon dioxide, hydrogen, butyric acid, and alcohol. 

 The bacterial colonies should be carefully cut out when 

 detected. 



Bacteriosis of Carnations. 



Arthur and Bolley have recently described a bacterial dis- 

 ease of carnations common in North America.^ It attacks the 

 leaves almost exclusively, causing pale spots which later become 

 whitish depressed areas. The plants are seldom killed outright 

 and the leaves remain attached, but they are stunted in size, 

 and the yield of flowers is prejudiced. The disease is favoured 

 by poor cultivation in moist surroundings, and is more prevalent 

 indoors. A very efficient remedy is to avoid watering the 

 foliage, except at long intervals ; by means of wire-netting it is 

 possible to water the roots without touching the foliage. (Edit.) 



Twig-galls of the Olive" (" liogna or Loupe "). 



Twigs of the olive are frequently beset with knots varying 

 from the size of peas to that of hazel-nuts. These consist 

 chiefly of parenchyma which begins to decay internally before 

 the gall has ceased growing ; finally the gall also dies. In this 

 way cavities in the twigs are formed in which Prillieux found 

 large masses of bacteria {Bacillus oleae), to whose action he 

 ascribes the formation of the galls, as well as the decay of the 

 tissues. Infection from pure cultures is yet required to show 

 whether the galls are really due to the action of the bacteria, 

 and whether the above-mentioned Bacillus is the real cause. 

 I had the opportunity of personally inspecting the disease on 

 olives near Iviva, and found that the galls really contained 

 nests of bacteria, while death of twigs above the galls was 

 very frequent. 



Similar symptoms of disease occur on willow, birch, pine, 

 and other trees, but they have not been investigated. 



1 Arthur and Bolley, Purdue University Agric. Exper. Station, Bull., 59, 1896. 



-Prillieux, " Les' tumeurs bacilles de I'Olivier, etc.," Revue gener. de 

 hotaiiique, 1889. 



