7 1 3 Boodle . — Anatomy of the Gleicheniaceae . 
(Fig. 8), or this mass may be broken up into three (Fig. 9). The 
difference between G. dichotoma and the Etigleichenia - type 
can be seen by comparing Figs. 9 and 7. Some of the phloem 
in the hooks of the xylem is converted into fibrous elements 
in G. dichotoma just as in G. dicarpa , and similar cavity- 
parenchyma is found in connexion with the protoxylem-groups. 
Cells which are evidently of the same nature as the cavity- 
parenchyma mentioned in- the Schizaeaceae (Boodle, ’01, 
p. 394) are found adjoining the protoxylems in the petiole 
of nearly all Gteichenias . They are cells which have evidently 
undergone extension towards the protoxylem-elements, either 
as the cause or effect of the crushing of the spiral tracheides, 
but in Gleichenia they generally have flatfish walls, as seen 
in longitudinal section, and so do not present the character 
on which the name ‘ Liickenparenchym ’ was based. Fig. 10 
shows three cells of this tissue ( cp .) in the petiole of G. dicho- 
toma. One of them has undergone late division ; and crushed 
protoxylem-elements are seen at px r . Throughout the genus 
it frequently occurs that a considerable number of the cavity- 
parenchyma-cells become rather thick-walled, pitted and 
lignified. 
A small part of the petiolar bundle of G. dichotoma is 
shown as a high-power drawing in Fig. n, where sc. is the 
left-hand end of the central sclerotic mass of Fig. 8. The 
sclerotic group is surrounded by an endodermis mostly torn 
(i.e .) ; px'. is part of a crushed protoxylem-group ; ph ' . and 
pph' . are the meta- and protophloem of the incurved phloem, 
and the terminal part of it is replaced by fibres f. Two of 
these probably represent sieve-tubes, and the other two 
phloem-parenchyma. The sclerotic elements in Fig. 12 are 
some from the central mass in G. dichotoma , shown in 
longitudinal section Many of the elements of this tissue 
are much longer, more pointed and thicker-walled (i. e. more 
fibrous) than those in the figure. 
Before leaving the petiole, one or two peculiarities of 
structure in certain species of Gleichenia deserve notice. 
In G. circinata a granular body, -apparently siliceous, was 
