Morphology of Phyllocladus alpinus , Hook . 261 
both cladode and normal axis there are a number of large lignified pitted 
elements. 
The most interesting point in the anatomy of the cladode is the occur- 
rence in the lateral bundles of centripetal xylem. This is remarkably well 
developed in P. alpinus, and also occurs, though less prominently, in 
P. rhomboidalis and P. trichomanoides. The centripetal xylem is not found 
at the base of the cladode, but only appears higher up. It is confined to the 
cladode, not occurring in the leaf (Fig. 6), the normal more or less cylindrical 
main axis (Fig. 7), or the axis of the male or female cone (Figs. 10 and 28). 
It consists of large tracheids which occur on the inner side of the protoxylem 
and also flank the normal xylem. These tracheids show the sculpturing 
which one is accustomed to associate with Taxinean wood, — the combina- 
tion, namely, of scalariform or spiral thickening with bordered pits. The 
elements of the normal xylem are also marked in this way, though to 
a less conspicuous extent. Figs. 3 and 4 show radial and transverse 
sections of a lateral cladode bundle with well developed centripetal xylem. 
Taxinean sculpturings are not confined to the wood of the cladode, but 
occur also in that of the leaf, the young part of the main axis, and the axes 
of the male and female cones. (I have not had an opportunity of examining 
an old axis.) We will consider the possible significance of these facts 
later on. 
III. The Reproductive Organs. 
A. The female cone . 
The female cone consists of a branch arising in the axil of a scale leaf 
and bearing a number of succulent bracts in the axil of each of which 
grows a single erect ovule. The bracts are as a rule, but not always, 
decussate. The best-developed cones which I examined had two pairs 
of fertile bracts at the base, succeeded by several sterile ones which had 
fused with the cone axis into an irregular terminal mass. Often two 
or three cones are closely clustered together, in which case the number 
of bracts and ovules in each individual cone is apt to be reduced to two. 
The stalk of the cone contains a ring of normal collateral bundles (Fig. 10). 
The appearance and structure of the cone and ovule shortly after pollination 
(which appears to occur in October) will be understood from Fig. 1 and 
Figs. 8-16. The nucellus contains the endosperm, surrounded by a well 
marked megaspore membrane, and is free right down to the base (Fig. 11). 
It is surrounded by a thick integument which is strengthened by a fibrous 
layer a little below the surface. After pollination the closure of the micro- 
pyle is effected by the growth and tangential division of the epidermal 
cells (Figs. 12, 13, A and b). The arillus at this stage is a mere ring-like up- 
growth round the base of the ovule. No vascular strands enter the integu- 
ment ; they terminate in a tracheal platform below the base of the nucellus. 
