394 West. — A Contribution to the Study of the Marattiaceae. 
grown plants of Marattia fraxinea and of Angiopteris evecta , the stem-apex 
is devoid of an apical cell, the meristem being referable, in some cases 
at least, to a group of four or five initials of exactly similar size and shape, 
which meet at the intersection of two more or less perpendicular lines. 
Charles (23), working on Marattia alata , gave a full account of the 
series of stages of increasing complexity which lead up to the formation 
of a meristem of several cells at the stem-apex of the older plant. 
The present writer’s observations on the structure of the stem-apex in 
a large number of young sporelings of Danaea alata , Sm., and of Danaea 
nodosa , Sm., confirm Campbell’s (20) account of the apical growth in young 
plants of this genus, a single very distinct apical cell being found at the apex 
of the stem of every specimen examined. This apical cell varies consider- 
sporeling showing the apical cell. b. Longitudinal section of stem-apex of a very young sporeling 
showing the apical cell, x 350. 
ably in shape, but generally has an irregular triangular outline in transverse 
section (Text-figs. 20, A, and 21, a), whilst in longitudinal sections it appears 
as an elongated cell which may be either pointed or truncate below (Text- 
figs. to, B, 20, B, and 21, B). In slightly more advanced sporelings, the apical 
cell appears roughly four-sided in transverse section, and is generally more or 
less truncate below. At a later stage one or more lateral segments of the 
apical cell do not pass over into permanent tissue, but retain their meri- 
stematic condition indefinitely, and thus become the equivalents of, 
and assume a similar function to, the original apical cell. In other 
words, each of these cells contributes to the slow growth in length of the 
stem by dividing periclinally ; consequently, at the apex of large well-grown 
stems, a meristematic region, such as that represented in Text-figs. 22 and 
23, is found. 
Campbell (20) states that in Kaulfussia the apical cell of the young 
rhizome is roughly triangular in transverse section, and oblong with 
a broadly truncate base in longitudinal section, but gives no account of the 
