526 Brebner . — On the Anatomy of 
matters are not complicated so early by the influence of the 
root as is the case in Angiopteris , which gives off a root 
nearly opposite the first leaf-trace 1 . The parenchyma marked 
p. in Fig. 13, PL XVI (Farmer and Hill, loc. cit), and called 
pith, is probably simply due to the root-junction and prepara- 
tion for the departure of the leaf-trace. In Danaea simplici- 
folia , then, the xylem of the first leaf, or cotyledon-trace, 
is marked off from that of the haplostele by a layer of 
parenchyma, and this increases in amount till the leaf-trace 
becomes free. The leaf-trace is collateral, and phloem appears 
on the side of the haplostele facing the departing trace-meri- 
stele, and thus becomes repaired or restored. This repairing 
phloem, at higher levels, sometimes makes its appearance in 
the intrastelar parenchyma before the leaf-trace becomes free, 
and might be interpreted as phloem appearing in pith. This 
process of giving off a leaf-trace with restoration of the 
haplostele is repeated several times, varying in number with 
the seedling and more or less affected by the junction of roots 
with the haplostele 2 . This is, therefore, nothing more nor 
less than the usual mode of departure of a leaf-trace from 
a simple rod-like stele, i. e. haplostele. Although, in the 
early stages of development of the vascular system, the suc- 
cessive departure of leaf-traces with resumption of the haplo- 
stelic condition seems to be the rule, one seedling showed 
a striking variation. It had in all six leaf-traces fully 
differentiated. Instead, however, of the usual mode of 
behaviour, the xylem soon showed parenchyma among the 
tracheids, which was at first irregularly distributed, but later 
occupied a central position (cf. Fig. 6). The appearance at 
this stage somewhat resembles the state of matters figured 
by Leclerc du Sablon for Angiopteris 3 , and the central 
parenchyma might be called a pith. The unusual condition 
was due to abortion of the cotyledon-trace, and preparation 
1 Farmer and Hill, loc. cit., p. 376. 
2 In this there seems to be no essential difference from what happens in Angiopteris 
(Farmer and Hill, loc. cit., p. 385) except for the presence of a pith in the latter. 
3 Loc. cit. 
