Barber . — Cupressinoxylon vec tense. 359 
masses of dark substance give the parenchymatous cells 
a vacuolated appearance 1 . This peculiarity has been of great 
service in the search for parenchyma in each section (cf. 
Figs. 8 and 9). Transverse walls are always found in the 
immediate neighbourhood of such masses, as if the contents 
had accumulated here during the disintegration of the wood ; 
and these transverse walls alone determine the parenchyma. 
There is thus some reason for the frequent description among 
the older writers of ‘ fossil resin ’ and ‘ fossil starch.’ 
The strands of wood-parenchyma occur as isolated rows 
of cells separated by transverse walls. In tangential sections 
the terminal cells of each row have pointed free ends, whereas 
in radial sections the end cells appear to terminate abruptly 
at a medullary ray just as many of the tracheides do. This 
suggests that each strand has an origin similar to that 
of a tracheide — from a single cambial cell. Occasionally 
several strands appear close together, and they are more 
abundant in certain sections or parts of sections. But 
generally speaking, the resiniferous tissue may be described 
as uniformly distributed. 
The cells differ in appearance in radial and tangential 
sections. In the latter the transverse walls cut the cells 
across at sharp angles, sometimes slightly obliquely, and 
the whole strand is of equal width excepting at the ends 
(Fig. 9). In the radial view, on the other hand, the 
transverse walls are never oblique, the cell- lumen is 
rounded at each end, and there is usually a distinct con- 
striction in the width of the cell at each division (Fig. 8). 
These facts are of considerable importance. In the first 
place, the shape of the wood-parenchyma-cells has been 
regarded as of great value by some writers 2 ; and secondly, 
various species have been characterized as having rows 
of cells constricted at intervals. Andrae, in an all-too- 
short description of Calloxylon Hcirtigii—d. Cupressinoxylon 
1 This vacuolated appearance has been noted by Kraus, Mikr. Unters., and drop- 
like masses of a similar nature have been described by Andrae. 
2 Hartig, according to Kraus, Mikr. Unters. 
B b 2 
