594 Davey. — Seedling Anatomy of certain Amentiferae . 
to be differentiated, while centripetal development proceeds from the 
central group. The lateral metaxylem of the cotyledonary triads persists 
downwards to a lower level than does that of the ‘ plumular ’ triads (Figs. 14, 
15, and 16). Neighbouring phloems are slow in coming together, but 
in most cases a root stele was attained, showing from eight to fourteen 
equivalent protoxylem poles alternating with phloem groups. A wide 
pericycle and a well-defined endodermis are present in the root, and are 
continued up into the hypocotyl. In the youngest seedlings no root stage 
was observed, since the triad units persisted downwards independently 
as far as differentiation could be demonstrated. 
It seems clear that the additional units of the hypocotyl and of the 
root are organized in continuity with the plumular strands found at higher 
levels ; but the feebleness of differentiation in the upper regions of young 
seedlings, which is rapidly succeeded by cambial development in older 
stages, renders their exact connexion difficult of observation. 
Fagus sylvatica. This is a large seedling of the epigeal type. The 
cotyledons, which are fleshy and much folded, are slow in expanding, and 
the elongation of the plumular axis is much retarded. All the plumular 
leaves are of the normal foliage type, the first two being opposite. The 
cotyledon petioles contain four lateral strands approximated in lateral 
pairs. These diverge to form the leading veins of the broad fan-shaped 
lamina. There is no indication of the central strand either in petiole or 
lamina. The vascular supply recalls that of the bifurcated cotyledons 
of Juglandaceae. At the base of each cotyledon petiole the four vascular 
strands are organized as double bundles. Eight of these enter the hypo- 
cotyl in diagonal planes, producing a symmetrical octarch structure. Meta- 
xylem and phloem diverge more widely from the central protoxylem, 
which gradually assumes the exarch position. Throughout the long hypo- 
cotyl and for some distance below the collet the stele consists of eight 
triad groups ; eventually the neighbouring phloems unite and an octarch root 
results. A large pith extends throughout hypocotyl and root. 
The cambium, which begins its development in the upper part of 
the hypocotyl, is at first active only within the limits of each triad. Meta- 
xylem and phloem become linked by secondary tissue, while the protoxylem 
disorganizes ; so that the stele appears to consist of eight endarch bundles. 
A well-marked endodermis is present in the root and extends upwards 
throughout the greater part of the hypocotyl. A large number of seedlings 
examined at different stages failed to reveal any variations or irregularities 
such as were found in Quercus . 
The seedlings of Fagales are of some interest, because they include 
examples of most of the known types of seedling anatomy together 
with forms showing transition from one to the other. Diarchy occurs in 
Betala and in certain species of A Inns. Alnus cordifolia shows diarchy 
