EDGAR TULU; 



851 



false heart wood formation^ which, through the action of fungi and bac- 

 teria, can be transformed to heart rot-. 



This attack by micro-organisms has led to the establishment of a num- 

 ber of parasitic diseases, which, however, essentially arise from disturbances 

 in the process of wound healing. As first in importance, we will name 



Wound Gum. 



Prillieux describes this disease as "Gommose hacillaire," and Viala as 

 "Roncet." The leaves remain green but become irregularly cleft and de- 

 formed. In cross section, the wood shows black points and specks which 

 enlarge and loosen its structure. Later the phloem separates from the 

 xylem. On the cut surfaces from which the disease spreads, clefts arise 

 which are infected by saprophytes. Prillieux found that the plant died 

 after three to five years. 



The black points in the wood arise from a brown, gummy deposit, which 

 fills the vessels and cells of the wood parenchyma and swarms with bacteria 

 (motile rods). Prillieux found in an infection experiment, made in May 

 in the laboratory, the characteristics of the disease, which bear great resem- 

 blance to those of Baccarini's "Malnaro." 



Viala and Foex, as well as Mangin, disagree with Prillieux, in that they 

 hold that the described phenomena of disease can be produced by very dif- 

 ferent causes and are not absent even in healthy plants. 



This difference in opinion was settled by Rathay^, who proved first of 

 all that gum can occur in perfectly healthy vines. He found gelatinous 

 threads in healthy, one-year-old shoots of Vitis riparia, extending from the 

 ducts and composed of gum. The vessels filled with gum {"gum cells") 

 may be seen in Fig. 202, /. This gave the color reactions of the pentoses. 

 In Vitis vinifcra, V. Labrnsca, V. Solonis, V. ariaonica, etc., the reaction is 

 found only in wood two or more years old. If this process occurred in young 

 vines, it could not be observed until July, when the gum is pressed out. In 

 the root, gum formation is less abundant. 



As Rathay reports, even in the grapevine, a normal heart wood forma- 

 tion may set in finally in plants twenty years old but takes place irregularly 

 since scattered places of the inner sapwood are involved in the change and 

 produce the brown spots, which Prillieux has described as the symptoms of 

 Gummose hacillaire. When such a brown place, extending backward like a 



1 Tuzson, J., Anatomische und mykologisclie Untersuchung-en iiber die Zer- 

 setzung- und Konservierung- des Rotbuchenholzes. Berlin 1905, cit, Centralbl. fiir 

 Bakt. 1905, II, Vol. XV, p. 482. 



2 Herrmann, tJber die Kernbildung bei der Buche. Naturf. Ges. Danzig-; cit. 

 Bot. Centralbl. 1905, Vol. XCIX. 



3 Rathay, E., tJber das Auftreten von Gummi in der Rebe und iiber die "Gom- 

 mose bacillaire." Kremla, H., tJber Verschiedenheiten im Aschen-Kalk- und 

 Magnesiagehalte von Splint-, Wund- und Wundkernholz der Rebe. Jahresber. d. k. 

 k. onolg. u. pomolog. Lehranstalt in Klosterneuburg. Wien. 1896. 



