62 THE OAK 
the true fibres and tracheids; they occur in those parts 
where masses of true fibres abut on the groups consist- 
ing of vessels and tracheids. They resemble tracheids, 
but have very few and small, scarcely bordered, oblique, 
slit-lke pits: every stage can be detected between these 
and true fibres. They must be looked upon as, so to 
speak, abnormal, because their numbers are small com- 
pared with the typical elements among which they 
occur. 
The wood-parenchyma consists of vertical groups of 
short cells, each group having the fusiform shape of a 
tracheid (fig. 16, w.p) : hence the upper and lower cell of 
each group has a pointed end. Each group obviously 
arises from the transverse divisions of a long, prismatic 
cell, pointed at both ends—a cambium cell. The trans- 
verse section is round, and somewhat larger than that of 
a tracheid, and the walls are somewhat thinner. Where 
they abut on vessels and tracheids their walls have 
bordered pits, but where they stand in contact with 
similar groups, or with parenchyma rays, the pits are 
simple. During periods of rest they are loaded with 
starch grains. 
The length of the groups—i.e. of the fusiform cells 
cut up into short cells—varies; the shorter ones have 
only one transverse division. 
The wood-parenchyma is less abundant than the 
tracheids and fibres, and predominates in the more 
vascular parts; after two to four or more fibres in a 
radial row a single parenchyma cell may often be seen, 
