542 
Bancroft.—A Contribution to our 
Frequently in a stems and occasionally in those of /3 type the contents 
of the cortical cells are preserved (PI. XXVI, Figs, i and 4, and Text-fig. 6), 
showing very varied conditions of blackening, granulation, and contraction ; 
here again the appearances may be due to petrifact, although Hick 1 
is inclined to attach some systematic importance to them. On the whole 
the cortical cell-contents of (3 stems are less blackened than those of a stems ; 
representative examples are shown in Text-fig. 6. 
With regard to the epidermal cells and hairs, Hick 2 has remarked that no 
contents are recognizable. In cases, however, where the cells are preserved 
in a growing state, as they are just above a place of branching, delicate, 
granular and vesicular contents may sometimes be detected. The multi¬ 
cellular hairs, when fully grown, appear to be appressed rather than spread¬ 
ing, and consist usually of a single row of cells, the terminal member 
of which may be pointed or rounded (Text-fig. 4, c). The terminal cells of 
young hairs often present the appearance of glands, particularly when con¬ 
tents are recognizable. In some cases a hair appears to grow from a single 
basal cell; frequently, however, it is carried by a pedestal consisting of 
several small cells 3 (Text-fig. 4, b). In one of the examples figured the 
lower part of the hair itself consists of a double row of cells (Text-fig. 4, c), 
suggesting a transitional state between typical uniseriate hairs and flattened 
multiseriate ramenta. 
v. Branching .—‘Dichotomy’ of the stems, described by Hick 4 as 
1 equal division ’, takes place in both a and (3 types. In (3 stems the single 
protoxylem group divides, and in passing up the stem 5 the two resultant 
groups become more and more separated as the xylem strand increases in 
size (Text-fig. 8 and PI. XXVI, Fig. 9). At the level where it presents about 
twice its original dimensions, narrow thin-walled cells occur laterally, and 
their gradual inward extension separates two equal, or nearly equal, masses 
of tracheides, each having typically a single central protoxylem group (PI. 
XXVI, Fig. 8 ; Text-fig. 8). 6 As the strands separate in passing upwards, 
each becomes surrounded by phloem and endodermis, so that the stem, just 
below the actual bifurcation, contains two similar steles which are destined for 
the two branches of the dichotomy (PI. XXVI, Fig. 8 ; Text-fig. 8, K 21 r). 
In the division of typical a stems possessing several protoxylem groups, 
only one of these is concerned in the production of the branch, the initial 
strand of which seems to be provided by the division of that group 7 
1 1 . c., pp. 4-6. 2 1 . c., pp. 2 and 3. 3 Hick (’ 96 ), p. 2. 
4 1 . c., p. 9; PI. I, Fig. 2. Scott (’ 08 ), p. 333. 
B See foot-note 4, p. 533, concerning the acropetal method of description. In the paper quoted, 
Boodle also justifies the use of words signifying motion of vascular structures, as ‘ avoiding a lengthy 
periphrasis’ (page 107, foot-note 2). 
6 In Text-fig. 553, the occurrence of two protoxylem groups in one of the branch-steles is not 
typical; it appears rather to be a transitory condition than to have any connexion with branching. 
7 In the stem figured, the position of the protoxylem groups indicates the division of one of 
them, lower in the stem, to supply the branch, although none of the series examined shows the 
actual process. 
