West. A Contribution to the Study of the Marattiaceae . 375 
Danaea nodosa , Sm. 
In its development, the stelar system of Datiaea nodosa passes 
through a series of stages in elaboration identical with those described 
above for Danaea alata , while the stele of the adult rhizome differs from 
that of Danaea alata only in its larger proportions and perfectly radial 
symmetry, the leaf- and root-traces being given off equally all round the 
stem-stele ; a detailed description of the structure and development of the 
vascular system of Danaea nodosa is therefore unnecessary. 
However, an examination of the vascular anatomy of an ill-nourished 
adult specimen yielded interesting results. Judging from its slender 
elongated rhizome, on which definite internodes could be distinguished, this 
specimen had fallen upon evil days. 
The stele of this rhizome consisted of an outer network of vascular 
strands enclosing a ground-tissue parenchyma which was traversed by a 
single strongly developed commissural strand (Text-figs. 9, i, and 14, a). 
The leaf-traces, which are made up of several (4-6) strands, pass off from 
this outer network of bundles leaving large foliar gaps. But since the 
insertions of the spirally arranged leaves are widely separated from one 
another, the foliar gaps seldom overlap. In the internodes the commissural 
strand opens out into a solenostele (Text- fig. 9, ii-vi) and below each 
leaf-gap in turn branches into two almost equal parts, one of which 
functions as a compensating strand, joining on to the strands bounding 
the leaf-gap and closing it in front, whilst the other passes slowly across 
the central parenchyma towards the next leaf-gap above, where the same 
sequence of events is repeated. 
A root-trace usually joins the commissural strand in the internodal 
region and plays an important part in the formation of the solenostele, but 
sometimes the root-trace joins the outer lattice-work of bundles at the 
point where the compensating strand fuses with the main vascular cylinder, 
as is shown in Text-fig. 9, viii-x. 
Thus we find that the stem of this ill-nourished adult sporophyte of 
Danaea nodosa not only approximates in size to that of the sporeling, but 
it permanently retains a type of stelar organization which marks only 
a passing phase in the development of the vascular system of the normal 
sporophyte (cf. Lang, 44 , p. 51). 
It is possible that the ontogenetic evolution of the stelar system is here 
arrested at an earlier phase than usual, the requirements of the plant having 
become simpler. 
Adventitious Buds. In Danaea nodosa , Sm., adventitious buds arise 
from a group of meristematic cells situated at the extreme base of, and 
towards one side of the swollen leaf-base of the parent plant (Text-figs. 8, b, 
and 10, a). It has already been pointed out by Lang ( 45 , p. 706) that 
