AND THEIR BEARING ON STELAR THEORIES FOR THE FERNS. 
719 
shallow endodermal pockets. From the axils of 
leaf-traces c, d, and.h, pockets of varying length 
are decurrent through xylic gaps into the par- 
enchyma between the xylem-cylinder and central 
sclerenchyma. These pockets are of varying 
depth ; they are basally closed and contain tissue 
similar in structure to the inner cortex. In one 
instance (c) the base of the pocket is forked. At 
III a spindle of endodermis enclosing paren- 
chyma is immersed in the pith. As this spindle 
dies out it is followed upwards by a growing 
mass of tracheides, which in like manner dwindles 
to a vanishing point, leaving the stelar core com- 
pletely sclerotic. The general distribution of 
stelar tissues thus noted if similar to that already 
recorded by Boodle (5) for this species. Certain 
points of detail, however, merit special atten- 
tion. Fig. 7 represents a transverse section of 
the stele at I, and shows the shallow endodermal 
pocket already referred to (Pk.). The stelar core 
is a continuous mass of sclerenchyma separated 
for the greater part of its circumference from 
the xylem-cylinder by a selvage of thin-walled 
parenchyma. At several points this selvage is 
narrow, and at S the sclerenchyma abuts upon 
the tracheides. At T and U tracheides are 
isolated within the selvage, and may thus be in 
contact with the sclerenchyma. The impres- 
sion gained from many such sections is that the 
general distribution of these stelar tissues is 
fairly defined, but that intrastelar adjustments 
may occur. 
Fig. 8 represents a transverse section of the 
stele at II. From it, it will be again apparent 
that, by local increase or decrease of xylem, 
parenchyma, and sclerenchyma, an histological 
balance is struck within the stele. That the 
consequent variations from point to point in the 
proportions and distribution of the component 
tissues are purely intrastelar matters cannot be 
doubted. At W a group of endodermal cells is lodged in 
parenchyma. 
