492 BOTANICAL GAZETTE [DECEMBER 
Two types of wood parenchyma fibers may be distinguished in the 
wood of the sycamores, although these may grade somewhat into 
each other. The elements of one of these types are found adjacent 
to vessels, which they somewhat resemble and with which they 
communicate through horizontally elongated elliptical simple pits 
(fig. 2, A, sp). Small dotlike or circular bordered pits are also 
sometimes found in these elements which put the wood parenchyma 
fibers in communication with one another. The cross-walls between 
individual cells are usually slightly oblique and are pierced by 
numerous slightly bordered pits. The second type is larger, usually 
more tapering at the ends, and the individual cells composing it 
vary considerably in size and form, so that frequently one individual 
cell is found overlapping two other cells of the same fiber (fig. 2, B). 
The cross-walls are usually oblique, often approaching the vertical, 
so that the individual cells are often pointed at the end. This type 
is characterized by small round or dotlike, slightly bordered’ pits 
(fig. 2, B, bp), which put them in communication with pith ray cells 
and other wood parenchyma fibers. The walls in certain places 
are often locally thickened. 
Wood parenchyma fibers slightly separated by two contiguous 
vessels often connect by means of tubular outgrowths from their 
lateral walls (fig. 2, A and B, #). By means of these tubular pro- 
jections, which are usually pitted at the points where they join, 
wood parenchyma fibers communicate with one another. Fre- 
quently these projections end blindly. 
Intermediate fibers (fig. 2, C).—These resemble wood parenchyma 
fibers in the fact that their walls are irregularly thickened and that 
their ends are somewhat blunted. They more closely resem- 
ble the wood fibers in form, although broader and much shorter 
5 By some investigators a pit is considered bordered only when the pit canal 
widens out abruptly toward the outside of the cell wall, the outer portion forming 
an angle with the inner portion of the pit canal which opens into the lumen; where 
no such widening occurs the pit is simple. On this basis, however, all transitional 
forms between simple and bordered pits can be found in wood cells; hence the classi-, 
fication is merely an arbitrary one. It is thought best in the present paper to con- 
sider pits as bordered where the walls of the pit canals are not parallel and where they 
give the appearance of a border in longitudinal sections. 
