FILICES., 
i 
: 
z 
be ined, by sing the engravings to 
some oe dig 4 per hina in the West 
iginal drawings, now. in the 
of Dr Wri Edinburgh, were sent? 
ions were made on two 
of Aspidium and one Athyrium only, coincides 
Lindsay in a t one in the 
* But the figure of embryo, as observed 
1, is described with much more accuracy 
either of these writers, although he had an op- 
seeing only a single species, the Athyrium 
in a state of spontaneous germination.t 
, however, had the good fortune to observe, 
from i i 
commencement, the germinating process, in 
several species eee ee so clearly distinct, 
that they must be consi as belonging to different 
tribes, namely, the Polypodiacee, Aspleniaceew, and 
Pteridea ; and having traced the embryo from becoming 
visible as a dark green point, to its gradual expansion 
and final evolution as a perfect plant, we have succeeded 
fh 
7 
ef 
4 
 ” First Period. | 
; Fig. 1. Represents the seed-lobes somewhat magni- 
Getty. tied. dete sitar Usnetulig Vicible’to the nakerl eye, 
Exhibiting Fig. 2. The same highly magnified and reversed, to 
the author's shew its under side, with the mould adhering to the 
Feroieating central fibrils. 
sea Satoiatineeh endlsday dopaak 
embryoof —— Fig. 3. Represents evolving from the 
ierns. decals odaaling 1d the ersten af ths lothaiel the use. 
ral size. The circular 
frond. 
~ Fig. 4. Theseed-lobes reversed, to shew the true root, 
. Fig. 5. The lobes cut off, to shew the tuberous swel- 
ling of the young stem, with the young frond and root 
from ite. 
Fig. 6. the young plant with a second frond 
‘ same 
Hi 
i 
: 
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f 
i 
clade within their substance of the 
embryo, which they nourish, and, under necessary 
* Beytriige zur Naturkunde, iii. 75. 
} De Fructibus et Semin. Plantat.—-Pref. 47, 
327 
circumstances, finally develope; 3d, As in the dico- — Filices. 
tyledonous seeds, these aim organs,germinate from a 
Y sthetandligg she abner “ hd 
et notwi ing this general congruity with di- athouck 
cotyledonous plants, ferns, both in the structure of their they differ 
embryo and manner of inating, possess. characters in — 
* oe -a5 LY and manner 
ceniy Stinerehing them from aber phonts hither- *° goes 
ist, In other dicotyledonous plants, the seed-lobes, 
at least such as rise to the surface, are afterwards far- 
ther elevated by the growth of the young stem; but this 
cannot happen in ferns, whose seed-lobes, less perfectly 
divided, and, expanding horizontally only, attain their 
Ree before the developement of the other parts 
of their embryo. 
2d, In other dicotyledonous plants, on the contrary, 
the root immediately germinating, contributes towards 
the evolution of the other organs of the embryo, and re- 
ci ly, even to the expansion of the cotyledons them- 
selves ; whereas in ferns, previous to the shooting of the 
true root, the seed-lobes are nourished by minute fibrils, Tensporary 
invisible to the naked eye, shooting from around the radicles, 
centre of the seed-lobes, and adhering to the soft mould 
in the crevices of moist rocks, where they frequently 
germinate. In this state, these plants, like the larva: 
of many insects, have no similarity whatever to their 
future form, and must have been generally mistaken 
for young Hepatice, which, both in a) and man- 
yar ae they somewhat resemble. 
3d, In the seed-lobes of dicotyledonous plants, the sced-lobes 
vessels conveying the green juice towards the other or- cellular, 
gans of the embryo appear. elegantly ramified, distinct without the* 
from, the deeper green of the cellular substance ; where. vascular 
as in ferns, on the contrary, the lobes of the cotyledon, (77). oun. 
when examined by the microscope, seem to consist en- mon to the 
tirely of a network of deep green cellular substance, other dico- 
without the least vestige of ramified vessels, tyledones. 
By these peculiarities, then, the true ferns are charac- 
terised with much more precision, than by the circinate 
involution of their fronds ; a forrh of vernation which is 
common to them; with certain kindred tribes, such as 
the Botrychiacee, Cycadacee, Lycopodiacea, and Mar- 
siliacea, as we shall afterwards find. 
IL. Of the developement and peculiar Structure of the 
Stem of Ferns, 
Although, therefore, the filices, in the organs of their Gencral 
embryo, possess a certain degree of analogy with dico- view of the 
tyledonous plants, this analogy diminishes as the pro- ‘¢lope- 
cess of ination advances, On cutting across the evade 
stem of dicotyledonous trees at the end of the first sum- of the stem 
mer, three distinct parts are manifest ; the bark enve- in dicotyle- 
loping the nbalds nities circle of wood immediately un- — 
it, in centre a great proportion of spongy 
cellular matter, The stem thus formed resem~ 
bles a cone, whose summit is terminated by a bud, Du- 
ring the gfe a pn tt the stem preserves its ori- 
ginal shape, only the summit of the cone is extended, 
and its diameter en 2 oo REUSE ST, 
proportion of wood greatly increased, and 
matter diminished, while it 
the wood towards the 
+ Anleit. (Transl. 1807, Lond.) Pl. 1. Fig. 17. 
