TWIG-GALLS OF THE ALEPPO PINE. 533 



Twig-galls of the Aleppo Pine.^ 



The galls occurring on the twigs and branches of Pinus 

 halepensis are even larger than those on the olive ; they are 

 particularly common in the woods near Coaraze in the Maritime 

 Alps. The galls contain masses of bacteria situated in canals 

 and cavities in the parenchyma, and throughout the woody 

 tissues inside the galls. Prillieux regards bacteria as the cause 

 of the galls, and he believes that they penetrate the healthy 

 bark and form nests which kill the parenchyma. Experimental 

 infection has, however, not yet been carried out. 



Canker of the Ash. 



Sorauer^ regards the well-known ash-canker as the result 

 of the action of bacteria, but Noack thinks this improbable. 

 Bacteria were found in the canker-spots only in summer, and 

 might easily have got there accidentally after the formation of 

 the galls. Galls of the ash caused by attacks of the insect 

 Phytoptus may frequently contain bacteria. 



Canker of the Ivy. 



Lindau^ describes a cancerous formation on ivy- twigs, accom- 

 panied by death of portions of the leaves. The diseased places 

 contained slimy masses of bacteria, and the canker-spots, though 

 at first isolated by formation of wound-cork, continued to extend 

 till they reached the wood, which was ultimately killed. Pure- 

 culture and infection-experiments were not carried out, and the 

 author himself was unable to determine whether the bacteria 

 were primary agents in the canker- formation or only late arrivals. 



Lilac Disease. 



Sorauer* observed masses of bacteria enclosed in cavities in 

 young twigs of lilac which after becoming black-spotted had 

 in many cases broken over. The attack and the part taken in 

 it by the bacteria were not however investigated further. 



'Vuillemin, " Sur une tumeur du Pin d'Alep," Compt. rend., evil., 1888; 

 Prillieux (loc. cit.). 



^Sorauer, Atla-i d. Pflanzenkranhheiten ; Noack, " Der Eschenkrebs," Zeit- 

 schfift f. PflanzenhranlcheiUn, 189.3, p. 193. 



'^JAnAaw, ZeiUchrift f. Pflanzenkrankheiten, 1894, p. 1. 



■•Sorauer, Zeitschrift f. Pfiamenkrankheiteii, 1891, p. 186, and 1892, p. 344. 



