Heart Bot of Ftderoxylon utile (Sneezewood). 
221 
In the vessels I have not observed the fungus to bore directly through 
the walls, and here they appear to follow the pits (Fig. 12 (b) ), which are 
abundant. From what has been said above it will be evident that the growth 
of the fungus longitudinally through the continuous vessels and the 
wood prosenchyma will be more rapid than laterally, in which latter case the 
hyphae have to bore their way through the walls of the wood cells or are else 
dependent on pits. 
Yon Schrenk * has pointed out that the formation of sheets is largely 
dependent on the resistance of the wood cells, and whether they are closely 
packed or not, and as pointed out by him for Bolinia Pseudacacia, so I hold 
the same to be a very plausible theory also for the sheets formed in 
Ftderoxylon utile. 
Von Schrenk t has reported that the common form of destruction in 
Bohinia is for the wood cells to break up into small pieces owing to their 
w^alls being perforated by hyphae. The smallest pieces were shown to be 
wood, thus indicating that the destruction does not pass through the 
cellulose stage. 
In the material of Ftseroxylon utile examined I have never come across 
any small pieces of unaltered wood. The destruction here appears invariably 
to pass through the cellulose stage. In between delignified wood cells I have 
at times come across elements, especially vessels, which still gave lignin 
reactions, but these were never isolated into small pieces. The walls of the 
vessels are particularly resistant. 
Description of the Fungus. 
The fructifications or sporophores of Fomes rimosus are among the most 
conspicuous of the so-called " shelf " fungi which grow on living trees. They 
vary in shape, size, etc., and especially does this appear to be the case with 
sporophores obtained from different hosts. 
On Ftaeroxylon utile they are usually hoof- shaped (Fig 1) or applanate, 
and the sizes most frequently met with vary between 2-4-14 x 3-5-7'5 x 
l'5-5 cms. In young specimens the upper surface is smooth and fulvous, 
but with age it becomes concentrically sulcate and very much cracked or 
jagged. The cracks do not penetrate far into the mass of the sporophore, 
and are usually limited to the outer hard surface which in this fungus is not 
encrusted. With age the surface colouring varies between dark brown and 
purplish-black, and older specimens are frequently covered with moss, etc. 
The most recent layers, w^hich form the front of the sporophore, are charac- 
* Schrenk, H. von, "A Disease of the Black Locust {Rohinia Pseudacacia)," 
Miss. Bot. Gdn., Twelfth Ann. Eep., 1901, p. 21. 
t Op. ext., p. 26. 
