tgor] ANATOMY OF THE OSMUNDACEAE 397 
family Osmundaceae has heretofore been classed as monostelic, 
the existence of an internal endodermis in one of the species is 
therefore a matter of considerable moment, especially if it be 
regarded as a real phloeoterma. 
Between the internal endodermis and the xylem there is a 
cylinder of elongated parenchyma, rich in starch and protoplasm, 
and from two to seven cells in thickness. This layer is continu- 
ous with the medullary rays. In 0O. regalis, O. Claytoniana, T. 
barbara, and T. superba a similar but thinner layer it found as a 
rule, and the cells are always smaller and richer in contents than 
those of the medulla on which they border. 
THE MEDULLA.—The medulla is very large in this family, 
particularly so in O. Claytoniana, and consists of large-celled 
parenchyma. Most of the cells are partly filled with large 
Starch granules, but frequently some of them contain tannin, 
especially in 7. darbara. A brownish fluid may occur in inter- 
cellular Spaces, and in O. regalts within the cells themselves. In 
these regards there is often a striking resemblance between the 
parenchyma of the medulla and that of the internal cortex in the 
Same plant. But there yet remains to be described a still more 
significant phenomenon, namely, the occurrence in the pith of 
brown sclerenchyma of the same kind as is found in the external 
cortex (figs. rg and 20). This is probably a primitive feature, 
and in this, as in many other respects, O. cinnamomea proves to 
be most interesting. Out of forty-four pieces of stem, chosen 
at random, and representing a corresponding number of different 
plants of this species, twenty-five of the examples showed brown 
sclerenchyma in one or both ends. It occurs as a central strand, 
varying in size from a few cells to almost the limits of the pith, 
Or as several small strands irregularly arranged. Fig. 14 is a 
Photograph of the transverse section of a stem in which there is 
a large axile strand, and fig. 75 of one in which the scleren- 
chyma is entirely absent from the pith. Further it has the 
peculiar habit of being present at one level, but perhaps bot at 
another; so it is likely to be found in nearly every plant if the 
Stem be sectioned from end to end. 
