Boodle. — Anatomy of the Schizaeaceae. 397 
seen on some sieve-plates in the root of Dichsonia antarctica , 
and in the rhizome of Davallia elegans and Nephrodium 
Thelypteris. In Angiopteris evecta however the root and petiole 
showed no callus in the sieve-tubes ; but in an old petiole 
lumps of a substance staining rather like callus occurred in 
many parenchymatous cells of the ground-tissue. In the 
petiole of Todea barbara no normal callus appeared to be 
present, but irregular masses of a substance like callus were 
present in some sieve-tubes and other elements. In appear- 
ance it suggested a degeneration product of the cell-wall. 
It must be pointed out that where a negative result was 
obtained with azo-blue, the sieve-tubes of the plant may 
perhaps exceptionally or at some seasons produce callus. 
But from the nature of the results, it seems probable that 
callus is absent or only rarely formed in the Schizaeaceae 
and Hymenophyllaceae, but that its formation is general in 
the Polypodiaceae. No general deduction will be drawn as 
to the Cyatheaceae, Marattiaceae, and Osmundaceae, as only 
one example of each was examined. 
As the sieve-tubes of the Hymenophyllaceae were only 
shortly described in the previous part of this paper (Boodle, 
’00, p. 457), a few details may be added here. In Schulze’s 
solution the walls of the sieve-tubes of Trichomanes radicans 
stain slightly blue (distinctly bluer than the walls of the 
pericyclic cells), while the sieve-plates on the vertical walls 
are seen in surface-view as nearly colourless areas which 
often have several yellow-stained granules (probably of proteid) 
on them. The granules appear to be sometimes scattered 
indiscriminately in a sieve-tube, but are often distinctly grouped 
on the sieve-plates, and much less numerous on the parts of 
the wall destitute of sieve-plates. Nuclei are perhaps occasion- 
ally retained in some sieve-tubes, but are usually evidently 
absent, while they are constantly present in the adjacent 
parenchymatous cells. Fig. 47 represents two sieve-tubes 
and one adjacent pericyclic cell from the rhizome of Tricho- 
manes radicans. Sieve-plates with granules are seen in the 
sieve-tubes, and there is a much elongated nucleus (n.) in 
