488 I'OMES APPLANATUS ( I'l'-KS. ) WALLR. IN SOUTH AFRICA. 



stain with the above reagent, and this region is dotted in the illus- 

 tration. After conversion O'f the lignin into cellulose the cellu- 

 lose is digested by enzymes secreted by the fungus, and this is 

 evident from the cellulose ridges which project into the lumina. 

 The cell walls become thinner and thinner as a result of deligni- 

 fication and digestion of the cellulose, and ultimately, when 

 completely absorbed, the cavities formed become filled with 

 fungoid tissue. 



T ha\e not seen such large masses of fimgoid tissue as is 

 fre()uently met with in trees attacked by J'Oiiics riniosus Berk., 

 but thinner, more or less felt-like fmigoid tissue is easilv evident 

 v*hen diseased wood is split lengthwise. Plate 15 fl, is a photo- 

 graph of a piece of wood of lilack ironwood in which deligni- 

 fication has already taken place to a considerable extent. 

 Though enzymes were not specially tested for there can never- 

 theless be little doubt thai both delignification and the digestion 



of the resulting cellulose is caused by enzymes secreted bv the 

 fungus. 



The mycelium of the fungus, as seen highly magnified in 

 the wood and illustrated in Fi^-. 2, is composed of hyaline, 

 branched and septate hyphai. which measure 1.2 to 1.6 /a and 

 less, ifrequently 2.8 /a, in diameter, and are frequently decidedly 

 vacuolate, as shown in the drawing. For staining the myceliujn 

 in the host 1 emjjloyed methyl violet after first mordanting the 

 sections in tannic acid, and this method gave very satisfactory 

 preparations. Fig. 2 also shows the hy])hc'e of the fundus pass- 

 ing through the pits of the wood, and I have not observed the 

 fungus to bore its way directly through the cell walls. For the 

 hyph?e to get from cell to cell the presence of the pits in the 

 cell walls would appear to be essential. 



A yellowish deposit has been observed in the lumina of 

 the vessels, raycells, etc. These deposits are of frequent occur- 

 rence in the wood of trees attacked by i)ore fungi, and some 



