Ifi A DISEASE OF THE WHITE ASH. 



remain intact for some time, and are then gradually dissolved. In the 

 oldest parts of diseased wood they are no longer present. 



Wood partially destroyed in the manner just mentioned was stained 

 with potassium permanganate, HCl and NH^OH, according to the 

 method recently described by Maule." 



A dilute solution of the permanganate is allowed to act on the wood 

 for a minute. The wood is then treated with strong HCl until no 

 color is visible. A drop of ammonia is then added. The lignitied walls 

 stain a deep red, which in many respects defines the various parts of 

 the walls more sharply than the phloroglucin reaction. The parts 

 (PI. IV, iig. 1), which do not stain with phloroglucin do not stain Avith 

 the permanganate. The contrasting color between the lignitied and 

 delignified parts is even sharper. Maule claims that the permanganate 

 reacted with an ether compound in the walls even after the removal 

 of Czapek's hadromal. In the "delignified" wood cells of the ash 

 even this compound (if there be a separate compound which reacts 

 with the permanganate) is therefore absent. 



In the ash wood the white fibers are not pure cellulose. The same 

 is true of many similar fibers from oak wood destroyed by species of 

 Hydniim, or Polyporus igniarncs^ and probably of other white fibers 

 resulting from fungus action on wood. With chloriodide of zinc, the 

 best cellulose reagent we have, these fibers stain a yellow brown, not 

 blue. This would indicate that the change in the wall is not the same 

 as in many of the conifers, where the so-called lignin is destro3^ed, 

 leaving a comparatively pure cellulose, as determined by staining 

 reaction and macrochemical analysis. This subject is simply referred 

 to in this connection, as it will form the subject of a separate paper. 



The change to an impure cellulose takes place locally, and generally 

 very early in the course of the destructive action of the fungus. The 

 mass of Avood destroyed changes somewhat differently. The first 

 changes noticeable are in the medullary rays and immediately adjoin- 

 ing cells. Very fine fungus hypha3 invade these cells, and shortly 

 after the middle lamella disappear. Small cavities occur in thicker 

 parts of this layer, i. e., where several cells touch (PI. IV. fig. 3, o)^ 

 and these increase in size (/•), spreading laterally, until two or more 

 join. Ultimately the individual cells become entirely isolated, The 

 wood cells proper are gradually destroyed from within outward, the 

 middle lamella? remaining longest. The change from perfectly sound 

 wood to wood entirely dissolved is a very abrupt one (PI. IV, fig. 8). 

 The hyphas invade a cell and dissolve the wall. So rapid is this that 

 no intermediate changes can be found. A piece of completely rotted 

 wood, such as occurs in the center of a diseased trunk (Pi. I), is repre- 

 sented in PI. IV, fig. 8. A more resistant piece of summer wood is 



"Maule, C. Das Verhalten verholzter Zellinenihranen gegen Kalium permanganat, 

 eine Holzreaction neuer Art. (Beitnige zur wissenschaftlichen Botanik, Vol. IV. 

 Stuttgart, 1901.) (Reviewed in Bot. Cent., 89. 328, 1902.) 



