Hymenophyllaceae , Schizaeaceae and Gleicheniaceae. 517 
(.?.£•.). The inner endodermis in this case remains near the 
centre of the stele throughout its course, and only for a short 
distance encloses 1-2 sclerotic elements, resembling cells 
of the outer cortex ; elsewhere it surrounds soft-walled cells 
only, like those forming the inner part of the cortex. Another 
case of a well-developed internal endodermis should be 
referred to. It differs from the one just described in the 
following characters: it attains a greater size, and, in the 
region where it is best developed, contains a fairly large 
group of brown sclerotic elements (a maximum of about 15) 
together with a certain amount of thin-walled tissue; for 
the greater part of its course it lies not far within the xylem- 
ring, and opposite a gap in the latter ; for a certain distance 
it lies in this gap, and at one point a bridge of 1-2 endo- 
dermal cells connects this inner endodermis with the outer 
endodermis of the stele. There is, however, no communica- 
tion between the ordinary cortical tissue and the parenchyma 
or sclerenchyma contained within the inner endodermis. 
Although the following fact probably has little importance, 
it should be mentioned that, in this series of sections, the 
phloem curved slightly round one of the ends of the open 
xylem-band, and that, when the gap in the xylem became 
closed, two or three sieve- tubes were shut in, but only 
persisted in the periphery of the pith for a short distance. 
Deductions from the mode of occurrence of internal endo- 
dermis, &c., will be reserved until the internal tracheides 
have been described. 
Internal endodermis in Schizaeci was first discovered by 
Professor Tansley, viz. in S. malaccana ; the inner endodermis 
of .S'. dichotoma was found by the writer subsequently. 
4. Internal tracheides. The remaining peculiarity of 
.S', dichotoma is the occurrence, in certain parts of the mature 
stem, of internal tracheides x , of which two examples are 
1 There is no constant relation of internal tracheides either to nodes or to the 
branching of the stem. In two cases of dichotomy some internal tracheides were 
present, and in one of these an inner endodermis also, in the region of forking, but 
in other cases, where internal tracheides were present, there was no branching near. 
N n 2 
