720 G wynne- Vaughan. — Observations on the 
it is quite possible that some of the specimens examined were 
wrongly named. 
In Antrophyum plant agineum, another dorsiventral Fern 
with a reduced stele, the ground-tissue is not decurrent through 
the leaf-gaps into the stele at all. The centre of the stele 
is occupied by a mass of pericyclic parenchyma as in certain 
specimens of Vittaria elongata . The internal phloem is very 
scanty, and as stated by Jeffrey (loc. cit., p. 133) it is alto- 
gether absent on the ventral side of the stele. I can also 
confirm this author upon the absence of the internal phloem 
over the same region in Antrophyum reticulatum , but while 
he says that the internal endodermis is also absent, my speci- 
mens are distinctly and definitely dictyostelic ; the plant has 
already been mentioned as such on p. 6 95. 
If these cases be taken as illustrating the effect of reduction 
upon the different tissues of the stele in a dorsiventral rhizome, 
it is seen that, in spite of the dorsiventrality, the xylem is 
equally affected on all sides of the stele. The phloem, on 
the other hand, experiences greater reduction on the ventral 
side of the stele than on the dorsal. The pericycle does not 
appear to be reduced at all, being, in fact, relatively more 
highly developed than in an unreduced stele. It will now be 
remembered that none of these indications of reduction are to 
be found in the stele of Davallia pinnata, or in the Lindsay a- 
type of stele. 
The effects of reduction upon the stele of an erect stem 
with the leaves inserted in several rows all round it are essen- 
tially the same as those described above, allowance being 
made for the difference in habit. A good example of such a 
structure is provided by Adiantum Aethiopicum. The leaf- 
traces depart as small, very slightly curved arcs, leaving very 
small leaf-gaps which, so far as the stele itself is concerned, 
close up at once. The leaf-gaps in the xylem-ring, however, 
persist long enough to overlap, so that in a transverse section 
two or three separate strands of xylem may be found enclosed 
within the stele. The endodermis and ground-tissue as a rule 
do not dip in through the leaf-gaps at all, and even if they are 
