i8o Campbell— On the Development of 
root-quadrant, the divisions are irregular, and its limits are 
soon merged in those of the foot. From the first the divisions 
in the root take place with great regularity. After one 
complete set of lateral segments has been cut off, a cell is cut 
off from the outer face of the apical cell, forming the root-cap. 
Unlike other Ferns, this is the only cap-cell cut off, and all the 
other segments are lateral. The cap-cell divides later into 
two (Fig. 7 1 b\ and in these cells divisions continue to form 
where they join the rest of the epidermis, so that the young 
root is enclosed in a sheath formed of two layers of cells 
(Fig. 73). The lateral segments of the apical cell are 
shallow and arranged very symmetrically. The first wall in 
each divides it into an inner and outer cell, and from the 
latter is later developed the fibro-vascular bundle. 
The Foot. 
The divisions in the foot are more regular than is usually 
the case. This is especially noticed when sections are made 
parallel to the quadrant-wall (see Figs. 66, 72). The 
general arrangement of the cells is much like that of the 
cotyledon, but the divisions are much less numerous, especially 
the transverse walls, and the cells are therefore larger and 
more elongated. Corresponding with the upward growth of 
the cotyledon, there is an elongation of the foot, so that the 
base of the foot extends downward much beyond the base of 
the root-quadrant, which thus comes in the older embryo to 
appear lateral, and no doubt led to Berggren’s mistake of 
supposing that the root originated from the foot. 
The Subsequent Growth of the Embryo. 
The second leaf arises practically at the first segment of the 
apical cell of the stem, and each succeeding segment gives rise 
to a leaf. The longitudinal growth of the root is slow, although 
a large number of segments may be cut off from the apical 
cell ; but these remain flattened, and only elongate at a late 
stage in the development of the embryo. 
The fibro-vascular bundles are poorly developed and arise 
