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1901] ANATOMY OF THE OSMUNDACEAE 399 
show similar bands of phloem along the inner wall of the 
central cylinder of each branch (fg. zr). Cases have been 
described above, in which there is a complete cylinder of inter- 
nal phloem instead of the two isolated bands just referred to 
(jig. 2z). The internal and external phloem connect through 
the ramular gaps (fg. rr). Likewise the internal and external 
endodermis are in textural continuity through these gaps, so that 
there is free communication between the cortex and the pith 
(fig. 20). 
Sometimes the cortex lying between the two branches con- 
tains brown sclerenchyma which is continuous through the ramu- 
lar gaps with strands of the same tissue occurring in the medulla 
of the branches. Frequently in less vigorous plants a transverse 
section of the main axis posterior to the point of ramification 
shows a diamond-shaped piece of cortex surrounded by endo- 
dermis (fig. 72). Posteriorly this included piece of cortex 
becomes continuous with the medulla of the main axis (jig. 73), 
and anteriorly with the general cortex (fig. 17). 
Twenty-five forks of O. cinnamomea were selected at random 
and sectioned. Twelve of them presented the phenomenon of 
typical wide ramular gaps. Six of them were of the reduced 
kind just described. In five cases there were gaps in the xylem 
only, cortex and medulla never becoming continuous; and in 
two even the xylem did not open up (fg. 76). For reasons to 
be outlined later, the writer believes the wide gaps to be the 
most primitive. 
O. regalis presents a much degenerated form of ramular gap, 
for here only the xylem opens (fig. 79). In O. Claytoniana the 
degeneration is carried still farther, for as a rule there are no 
branch-gaps at all (fig. 28). In 7. barbara the xylem alone may 
Open up. 
The phenomena of the fork may be thus summarized : 
(1) Complete ramular gaps occur only in O. cénnamomea. 
(2) Internal phloem occurs only in O. cimnamomea. it is 
found in the branches just above, and in the parent axis just 
below the point of bifurcation of the central cylinder. 
