552 
Bancroft.—A Contribution to our 
Numerous examples occur of small axes in which the stele is reduced 
to a few tracheides surrounded by small thin-walled cells; there is no 
definite bundle-sheath (Text-fig. 16). The cells of the cortex are large, 
thin-walled, and irregular in shape. Usually the outermost cells are much 
crushed, or are entirely unrepresented; in a few instances, however, they 
may be seen to form a very loose tissue (Text-fig. 16, b) y perhaps com¬ 
parable with the assimilatory layer in the axes of Stauropteris oldhamia . 1 
The epidermis consists of narrow thin-walled cells which may produce hairs 
(Text-fig. 16, b). 
Text-fig. i6. a , b , and c, transverse sections of small axes associated with R. cylmdrica. In 
b , the outer cell-layers are shown at one point; ep ., epidermis, h ., hair, par., parenchymatous cells, 
separated by intercellular spaces, i. In c, the vascular strand has divided into two equal groups, v. 
x 80. (a, from slide K 21 d\ b, from K 21 e \ c, from K 21 a, University College, London.) 
Dichotomously branching examples of these axes have been observed 
in both transverse (Text-fig. 16, c) and longitudinal section. The size of 
the axes is very variable (Text-fig. i< 5 , a , b , and c) y and is difficult to 
determine, owing to the crushing and removal of the outer cells; the 
largest seem to be somewhat smaller than the monarch ‘ axes ’ described 
above. 
No gradations between these axes and either a or (3 organs of 
R. cylindrica have been observed. 
2. Sporangia . 
The sporangia which occur in association with R. cylindrica are 
rounded or oval in section ; the example shown in Text-fig. 17, a y measures 
325// by 400 fji. The sporangium wall consists of a single layer of cells 
which become enlarged locally, forming a pluriseriate annulus (Text- 
fig. 1 y,a); the inner and lateral walls of the annulus cells are usually 
somewhat thickened. 
1 Scott (’ 05 ), p. 115. 
