130 College of Forestry 
ments disappear with approximately equal rapidity. In the 
earlier stages of the decay the hyphe follow mainly the 
course of the tracheids and medullary rays. The lumina of 
the tracheids frequently become occluded by a dense growth 
of minute fungal hyphe. By the time pockets have been 
formed in the wood the fungal hyphze are found to be abun- 
dant in nearly all the woody elements, penetrating them in 
all directions and filling their walls with numerous perfora- 
tions. The perforations made in the walls of the elements 
are exceedingly minute at first but continue to enlarge until 
they become many times their original size. The hyphee 
frequently pass from one tracheid to another by means of 
the bordered pits on their radial walls. In such cases the 
entire pit — border and all — often is dissolved out entirely. 
The hyphz found in decaying hemlock wood as a rule are 
so fine and minute that their morphological features neces- 
sarily are indistinguishable. Occasionally, however, larger 
hypheze occur which lack protoplasmic contents and in which 
cross walls and clamp connections can be observed. In radial 
sections of decayed wood numerous mats of hyphe may be 
seen extending across one or more tracheids, occluding the 
cell lumen of each tracheid. These wefts of hyphee seem to 
be incrusted with a light brown substance — possibly certain 
by-products of decomposition. 
Tests for lignified and cellulosic tissue agree with one 
another in that they show a gradual delignification of the 
cell-wall, commencing at the lumina of the cells and proceed- 
ing outward, the thickened corners of the primary lamelle 
being the last elements to become delignified. The destruc- 
tion of the cellulose follows closely after delignification — in 
fact so closely that but little free cellulose is left temporarily 
in the partially decomposed cell-walls. From the closeness 
with which the destruction of the cellulose follows delignifi- 
cation it is evident why the pockets found in hemlock wood 
in the latter stages of decay always are so clean-cut and free 
from partially decomposed woody material which, in the 
majority of decays, usually consists of free cellulose. 
