384 BOTANICAL GAZETTE [NOVEMBER 
position in which the frond ordinarily grows, although a young 
frond may later develop within the same pouch. Behind the 
growing frond or flower there is a bud normally present. The 
rudiments of this bud appear very early in the development of 
the frond, in the axil of which it is located. Such a bud is shown 
in fig. 1. The frond subtending this bud was slightly smaller than 
that shown on the same scale in fig. 10. The development of the 
bud involves only elongation at first (figs. 3 and 4), but at an early 
stage there is a thickening of the basal region. The limitations of 
space soon force the elongating bud to turn from the nearly erect 
position to one more or less oblique and finally to the horizontal. 
This is less rapidly accomplished when the bud lies behind a flower, 
since in this case the developing seed by its bulk spreads the for- 
ward part of the pouch, and leaves immediately behind itself a 
space in which an erect development of the bud may go on for a 
considerable time; but even in this case the frond becomes hori- 
zontal while still minute. 
Differentiation of parts 
When the bud is about twice as long as the diameter of its base, 
the cells of the root initial may be distinguished. They are usually 
the fourth cell layer from the ventral surface, and develop a cleavage 
along the contact region of the third and fourth series of cells 
(figs. 5 and 8). The cells of the fourth layer and deeper develop 
the root cap and the root structures within the cap; those of the 
second and third layers are crushed by the elongation of the root 
tissue; but the outer layer elongates with the forward growth of 
the root and forms the “root sheath’? which commonly persists 
about the base of the mature root. 
At nearly the same time when the root develops there is formed 
upon the dorsal surface of the bud a slight elevation or mound of 
cells. This is nearly opposite the group of root initials and marks 
the origin of the bud for the next frond in the series (fig. 3). Very 
soon a second mound is visible, close to the insertion of the bud 
upon the parent tissue, just behind the bud of the daughter frond 
(figs. 7 and 7a). This is the inception of the bud axillary to the 
frond the development of which is being followed. This bud will 
