580 
MR. F. O. BOWER ON THE COMPARATIVE MORPHOLOGY OF THE 
Holle states ( l.c p. 218), I presume generally for Marattia and Angiopteris, 
though this is not made clear, that there is one wedge-shaped, pointed, apical cell at 
the apex of the young leaf, and that it may be found till after the appearance of the 
pinnae. He describes it as being neither two-edged nor three-sided, but of irregular 
transverse section, while its divisions appear without definite regularity. I have 
satisfied myself, by observation both of medial longitudinal sections of leaves of various 
stages of development, and of transverse sections of the extreme apex of the leaf, 
that there is no such wedge-shaped cell at the apex of the leaf of Angiopteris evecta: 
a result which coincides with Holle’s description, viz.: that there was irregularity of 
form and of succession of segments of the apical cell which he saw. Preparations 
were made by me from leaves varying in their state of development from the condition 
of a flattened papilla, to the period of formation of the pinnse, and the same result 
was obtained from all, viz.: that there is not any single, conical, apical cell in the 
ordinary sense of the words. 
My own observations show that the structure of the apex of the leaf of Angiopteris 
evecta is as follows. There are at the extreme apex a number of cells, larger than 
those surrounding them : as may be seen in median longitudial section, they are limited 
below by periclinal walls (Plate 37, fig. 12), and are thus clearly not wedge-shaped 
or conical cells. The cells of the apical region may be referred, in some cases at least, 
to a group of four initial cells (marked x in figs. 12 and 14), but these cannot 
always be equally well distinguished, and as seen in surface view from without, they 
exceed the surrounding cells but little, if at all, in size (figs. 13 and 14). These cells may 
be more clearly recognised when seen in a median longitudinal section of the apex of 
the leaf, in which case, of course, but two of them will appear. In such sections 
(fig. 12) the two cells appear separated from one another by a wall, which may be 
traced back continuously into the lower tissues of the leaf: they present an oblong 
outline, and exceed the average of the surrounding cells in depth. Passing away from 
the apical cell in either direction, the cells are seen to be smaller in average size : the 
prevailing mode of division is by successive periclinal and anticlinal walls, though, as 
may be seen in fig. 12, the succession of these is not strictly according to rule. 
A similar absence of regularity in the arrangement of the anticlinal walls may be 
seen in the figs. 13 and 14, which represent the apices of the leaves as seen from 
without. It is thus apparent that the arrangement of cells at the apex of the leaf of 
Angiopteris is similar to that described for the apex of the root.* 
As the pbyllopodium elongates, the pinnse make their appearance on the ventral 
surface of it, and above the level of insertion of the stipules. All the evidence at my 
disposal points to a development of the pinnse by monopodial branching of the 
phyllopodium in strictly acropetal succession, and in somewhat regular alternation on 
the two sides. They appear first as broad projections of the ventral face of the 
phyllopodium, and are arranged in two longitudinal rows, as in other Ferns (Plate 38, 
* Russow, Vergl. Unters., p. 107. Schwendener, Bot. Ztg., 1880, p. 718. 
