208 
Long . 
■Studies in the Morphology and 
In all six plants the solid xylem of the basal region becomes medullated 
a little below the first evident leaf-trace, but the plants present considerable 
variety in the transition from the basal region to the adult structure, and 
the differences are very marked in relation to the degree of development 
of an internal endodermis. While doubtless not exhausting the possible 
range of variation, these plants appear to afford sufficient data for a critical 
study of the nature of the internal endodermis in B. Lunar ia. Plants 
A and B have no internal endodermis in their gradual passage to the adult 
structure. In plant C there is a deeper inward ex- 
tension than usual of the endodermis at one long 
leaf-gap, but the internal endodermis is never com- 
plete. Plant D is similar to the preceding one, but 
the internal endodermis is completed for a short 
distance. In plants E and F there is a still more 
marked intermediate region in the rhizome, and 
the internal endodermis is complete for a consider- 
able distance, not only at the leaf-gap, but above 
and below this. 
In plant A (Text-fig. 3) the stele begins be- 
low with a slender solid strand of tracheides. In 
this, as it widens out, a small parenchymatous pith 
appears, and the medullated condition persists 
throughout the further growth of the plant. Before 
the preparation for the departure of the first re- 
cognizable leaf-trace is evident, five roots have been 
given off close together from the solid stele and 
lower portion of the medullated stele. No trace 
of any vascular supply to the scale-leaves, which 
were presumably related to these roots, was found. 
The first evident leaf-trace is very small, and dies 
out in the cortex a short distance from the stele ; 
the second is only a small strand, but reaches the 
base of what was evidently a large scale-leaf. The 
third passes out from the stele as a considerable 
trace, while the fourth and succeeding traces are larger and probably 
supplied the first green leaves. The departure of the first three leaf-traces 
involves no breach in the external endodermis, a complete reparatory band 
of endodermis being formed internal to the departing trace (cf. Text-fig. 2). 
The fourth and following leaf-traces depart from the stele, which shows 
a marked increase in diameter, according to the adult type (cf. Text- 
fig. 1). 
This is the plant described by Bower on p. 540 of his paper, and 
a section at the level of departure of the fourth leaf-trace is figured by 
Text-fig. 3. Reconstruc- 
tion of the stele of plant A. 
Description in text. 
