112 College of Forestry 
essentially the same as that described for yellow birch. The 
various kinds of elements, however, decay in somewhat dif- 
ferent order than in yellow birch, due to the entirely different 
structure of bitternut hickory wood. 
Cross sections of well decayed bitternut hickory wood 
when treated with phloroglucin-HCl, present a very striking 
appearance. After staining with this reagent one is able to 
see clearly that the elements disappear in a definite order. 
The vessel walls take on an intense red-violet coloration even 
when remaining as almost isolated elements in a completely 
decayed mass. The cells immediately bordering the vessels 
hkewise become colored deeply but the reddish-violet colora- 
tion is less intense than that exhibited by the vessel walls 
and diminishes rapidly in intensity so that a few cells away 
from the vessels this coloration is very slight or entirely lack- 
ing. Closer investigation, however, shows that the vessels 
usually are surrounded by a layer of wood parenchyma cells 
which, as will be shown later, also are very resistant to decay. 
Owing to this peculiarity and the fact that their walls were 
more intact it is apparent that the cells immediately adjoin- 
ing the vessels are less susceptible to decay or at least decay 
more slowly than the more distant-lying elements. The pith- 
ray cells, as evidenced by the deep coloration acquired by 
their walls and their resistance to decay, are second only to 
the vessels in resisting decay. The pith-rays frequently 
remain in place with the cell-walls moderately intact and 
exhibit a good coloration with phloroglucin-HCl, while the 
elements on either side may be considerably disintegrated. 
The wood parenchyma cells are decayed before the pith-ray 
cells but remain intact much longer than the wood prosen- 
chyma elements. Hickory wood, as explained earlier, is 
characterized by lines of wood parenchyma which extend 
tangentially between the pith-rays. In portions of decayed 
wood these two lines of elements can be seen remaining in a 
partially decayed state while the intervening spaces contain 
only the remnants of cells or may be entir ely empty (Plate 
XXIV, Fig. 2). 
