Boodle.—Anatomy of the Hymenophyllaceae . 477 
the leaf instead of one. Judging by the mature condition 
it seems that the protoxylem from a leaf may die out in the 
stem at some distance below its entry into the stele, without 
fusing with the protoxylem of other leaves, but this could 
not be proved in the material used. 
T. spicatum , Hedw. 
This is another species with an upright stem and two-fifths 
arrangement of leaves. The xylem of the stele here consists 
of a solid mass of tracheides and parenchyma, somewhat as 
in T. Prieurii , but of smaller dimensions, and the tracheides 
are of nearly uniform size, so that the protoxylem cannot be 
distinguished in the transverse section of the mature stem. 
A young stage shows that the first formed tracheides are 
scattered irregularly. They are not spiral, but are finely 
scalariform. The petiolar bundle is small, with a ring of 
metaxylem surrounding a little parenchyma, with a nearly 
central protoxylem, the phloem being interrupted on the 
adaxial side. Lower down, the metaxylem next the axis is not 
formed, so the bundle there contains a band or arc of xylem 
with the protoxylem on the side towards the stem k The 
leaf-trace in the stem is similar. Hence the protoxylem is 
likely to be embedded in the xylem of the stem, and some of 
the scattered protoxylem-elements in the stem are perhaps 
continuous with leaf-traces. 
T. Bancroftii , Hk. and Gr. 
This is also a species with an upright stem, and in structure 
it is very similar to T. spicatum , having no spiral protoxylem. 
The last three species all have rather thick-walled tra¬ 
cheides. The petiolar bundle has its xylem in the form of 
a straight band with a protoxylem at each end. The 
protoxylems do not interrupt the phloem, as stated by 
Prantl 2 . 
1 This change is the reverse of what occurs in Hymenophyllum dilatatum, &c. 
2 Prantl, l.c., p. 21. 
