238 DISEASE IN PLANTS. 



destroyed here and there, Frank refers the damage 

 to Phelloinyces. Where the dry-rot is due to 

 Fusariuui the chalk-white stromata may often 

 be detected breaking through the periderm ; but 

 it must be remembered that the soil-contaminated, 

 broken skin of a potato-tuber is a favourable 

 lurking spot for many fungi, and Periola, Acros- 

 talagnius, and others have been detected therein. 



Brown spots, depressed into the flesh, some- 

 times result from the ravages of Tylenchus, the 

 minute worms being found in the diseased tissues. 



In some cases the flesh turns watery and soft, 

 grey, almost glass-like, starting at the haulm 

 end, and this may be owing to the invasion of 

 Rhizoctonia. 



Notes to Chapter XXV. 



The rotting of bulbs, roots, etc., has been much discussed 

 during the last few years in the pages of the Gardeners^ 

 Chronicle, Zeitschrift fiir Pflanzeiikh.^z.Vid, elsewhere. The 

 principal references to Bacteriosis the rot in which bacteria 

 are stated to be the primary agent causing these and similar 

 diseases may be found in Massee, Diseases of Plants, pp. 

 338-342, and more fully in Russell, Bacteria in their Relation 

 to Vegetable Tissue, Baltimore, 1892 ; and in W\g\!\?i,Kritische 

 Uebersicht derjenigen Pflanzen-krankheiten, ivelche Ange- 

 blich dtirch Bakterien vernrsacht werdcn, Semarang, 1892. 



The most convincing accounts, however, are since that 

 date; see Smith, " Pseudomonas Campestris," Cent./. Bakt., 

 B. III., 1897, p. 284, and Arthur and Bolley, Bacteriosis of 

 Carnations, Perdue University Agr. Expt. Station, 1896, 

 Vol. VII., p. 17. Woods has lately shown that this disease 

 is due to Aphides only, the bacteria having nothing to do 

 with the disease primarily, Siigmonose, Bull. 19, U.S. Dept. 



