269 
A ngiopteris evecta , Hoffm. 
Osmunda as described by Bower 1 ; however this may be, it is 
a fact of some importance that in a number of cases at any 
rate, the root-apex in the embryo contains a group of meris- 
rnatic cells, instead of the single apical cell so characteristic 
of the leptosporangiate ferns. 
The vascular bundle of the embryo is formed at an early 
age, and is first differentiated in the cotyledon ; it joins directly 
on to the bundle of the root, the first tracheids appearing 
at the point where the leaf-trace curves into the stem, and 
from thence fresh ones are differentiated in an upward and 
downward direction. The vascular bundle is accompanied in 
the cortex surrounding it, by rows of cells containing tannin 
(Figs. 11, 12). These are differentiated in the embryo at 
a very early age, long before it issues from the prothallium. 
Their development is best observed in the cotyledon, where 
they are seen to arise as cells, which elongate with the growth 
of the leaf, and finally coalesce by the disappearance of their 
transverse septa much as do the cells composing the latici- 
ferous tissue of Chelidonium. I saw no instance of any lateral 
extension of these tannin-cells, though sometimes short blind 
protuberances are pushed between other cells of the cortex. 
When the embryo has reached a certain size, it bursts the 
prothallium, the root boring through the lower surface, whilst 
the cotyledon and stem break through the cells of the upper 
surface. This manner of issuing from the oophyte serves at 
once to distinguish Angiopteris from those other ferns whose 
embryogeny is known ; for it will be remembered that in them 
the cotyledon and stem appear through the archegonial region 
on the lower surface, and, so to speak, grow up round the 
edge of their prothallium. The peculiarity of Angiopteris in 
this respect may be connected with two facts in its earlier 
history ; namely, first, with the occurrence of the archegonia 
at some distance behind the apex of the somewhat large 
oophyte, and secondly with the position of the basal wall 
which separates the shoot and root portions of the embryo, it 
1 Bower. Comparative examination of the meristems of Ferns : Ann. Bot. Ill, 
p. 3io- 
