398 BOTANICAL GAZETTE [DECEMBER 
This same habit is characteristic of its appearance in O. 
regalis (fig. 20), but more often it is not present at all. That 
brown sclerenchyma occurred in the pith of O. rvegalis did not 
escape the observant DeBary,” but elsewhere I find no reference 
to this fact. Strangely enough, however, out of thirty-five or 
forty plants harvested from one locality there was not a trace of 
sclerenchyma to be found in the medulla of any of them, while 
in one region not far distant 25 per cent. showed this phenome- 
non, and in another a still higher per cent. 
Parenchyma is the sole constituent of the medulla of O. Clay- 
tontana (fig. 17). This is probably true of 7. superba too. fig. 
25 is a cross section of 7. barbara taken too near the growing 
point to show sclerenchyma, but farther down the medulla was 
occupied by a large strand of this tissue (fig. 2). 
Thus medullary brown sclerenchyma is usually present in O. 
cinnamomea, in O. regalis not uncommonly, and in O. Claytoniana 
not at all. In 7. darbara it also occurs, but apparently not in 
T. superba. It is perhaps significant that such series can be 
arranged, but of greater importance is the fact that the occur- 
rence in the Osmundaceae of brown sclerenchymatous tissue, 
apparently within the cauline central cylinder, has no parallel 
among existing ferns. 
THE FORK,—There yet remains to be described the anatomy 
of one particular portion of the stem, the part in the region of 
bifurcation. It has been stated that it is peculiar to the stem of 
the Osmundaceae to fork once, and that in a horizontal plane. 
We shall treat first of the phenomenon in O. cinnamomea. Trac- 
ing the main stem forwards, it is seen to become flattened and 
then to become constricted in a median vertical plane. Imme- 
diately anterior to the point of bifurcation of the vascular axis, 
there is a wide ramular gap in the céntral cylinder of each 
branch (fig. ro). Sections of the main axis immediately below 
the fork show two bands of phloem, one on the upper and one 
on the lower internal surface of the central cylinder (fg. 13). 
Sections passing through just in front of the region of bifurcation 
2° DEBARY: of. cit. Pp. 290. 
