STUDIES ON THE LIGNIN AND CELLULOSE OF woop. 53 
manner that it can have little or no effect upon the final . 
result where the delignification is extensive, as is shown 
quite conclusively a little later in this paper. 
The cellulose which is so often found in wood undergo- 
ing the last stages of decay is the cellulose skeleton or 
framework of the secondary, lignified layer which is uni- 
versally present in old wood fiber walls, whether they have 
the supernumerary cellulose layer or not. That this is so 
is proved by a careful examination of the various stages of 
rot caused by any one of the numerous wood rotting fungi 
which delignify woody cell walls. The published work and 
drawings of Robert Hartig * alone are sufficient to prove this, 
as it has been found by the writer that cultures from rot- 
ted wood in the middle of a decayed stem of a living tree, 
if the exterior layers of wood are still alive, invariably 
yield but a single fungus, thus proving that the attacking 
fungus occurs in a pure state at least in most cases. If 
there is any cellulose layer present in the wood before it is 
attacked it is probably the first part of the cell wall to be 
dissolved and it is fairly certain that it does not exist in the 
last stages of decay. 
Two instances of trees attacked by wood rotting fungi 
which fully bear out the last statement have recently come 
to the writer’s attention. 
A tree of Carpinus Caroliniana was found badly de- 
cayed by Polyporus gilvus,t which in this case seemed to 
be a wound parasite. At the edge of the affected wood 
was a narrow border of dark, infiltrated cells separating 
the healthy from the diseased wood. In the healthy wood 
just outside this infiltrated zone the wood fibers in many 
cases had an inner, lining layer of cellulose. This layer 
disappeared in the infiltrated zone while in the very badly 
* Hartig. Wichtige Krankheiten der Waldbéume. 1-127. (1874); 
Die Zersetzungserscheinungen des Holzes der Nadelholzbiume und der 
Eiche. 1-151. (1878). : 
+ Engler & Prantl’s Pflanzenfamilien is followed in naming the fungi. © 
