SOLVENT ACTION OF BACTERIA-DESTRUCTION OF MIDDLE LAMELLA-BACTERIAL 

 SOLUTION OF CELL-WALLS-FERMENTATION OF CELLULOSE- 

 DESTRUCTION OF WOOD. 



Next to crushing and splitting, due to the rapid multiplication of the bacteria in closed 

 spaces, solution of the middle lamellae uniting cell-walls is probably the most widespread and 

 simple action of bacteria on plant tissues. This is common in a great number of diseases, 

 but it is not always possible clearly to separate lysis from tension-splitting, when the bac- 

 teria are multiplying rapidly in a given tissue and must have room. An excellent example 

 of the separation of cells by a solvent action on the pectic matters composing the middle 

 layers of the common wall may be seen in various rots of potato-tubers. A few days after 

 an inoculation the tissue softens, and if it is then washed in water the cells float free, their 

 starch content remaining unacted on (fig. 25). Potter asserts this solution to be due, in case 



of a turnip rot which he studied, 

 to the presence of oxalic acid. 

 The writer found oxalic acid had 

 no solvent action on slices of 

 turnip, but that ammonium oxa- 

 late softened the middle lamellae 

 decidedly. Inasmuch as a part at 

 least of any oxalic acid liberated 

 by any Schizomycete of this type 

 would be converted into ammo- 

 <wtUL?1 J&/Z: XJC& nium oxalate by the evolution of 



ammonia due to the continued 

 growth of the organism, it is not 

 unlikely that ammonium oxalate 

 is the substance, which in some 

 cases, dissolves the middle lamellae. 

 It would seem, however, that 

 Flg - 25 * in many cases a specific enzyme, a 



pectase, must be the solvent body. Vide paper by Spieckermann and papers by Jones. 



Once or twice in earlier papers the writer has used the word "cellulose" loosely, in the 

 old way, for cell-wall, of which it forms, however, only a part. When the middle layers of 

 pectic origin have been destroyed there yet remains a wall of cellulose surrounding each cell. 

 Is this permeable to bacteria? Can any of the bacterial plant parasites dissolve it? No 

 such crucial studies have been given to the subject as Omelianski, for instance, has given to 

 the solvent action of the anaerobic organisms of marshes known as the methane bacteria. 

 It has been demonstrated that the marsh-gas bacteria destroy cellulose in large quantities, 

 but nothing like that, of course, occurs in the diseases in question. All we know definitely 

 can be expressed in few words. 



Bacteria certainly find their way into the interior of cells which have not been crushed 

 or mutilated. The evidence of this is the fact that they are so found in great numbers and 

 inside cells under conditions which seem to preclude entrance through wounds of any sort. 

 How do they enter? Their entrance is an extremely difficult thing to observe owing to their 



*FlG. 25. Softened tissue from interior of a potato tuber inoculated with Bacillus phytophthorus and kept for 

 6 daysat about 2$ r C. Cells have separated, by solution of middle lamella-, but starch grains are intact. Oct. 26, 1906. 



76 



