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C H A P T E R I I .
GENERAL OBSERVATIONS.
T h e plants constituting the family Sphagnacece, and known as
Peat-mosses or Bog-mosses, have long attracted notice from the
ordinary observer by their peculiar aspect and habit, and have
equally interested the microscopist by the beauty of their tissues,
and exercised the botanist by the difficulty which attends their
correct determination ; the latter perhaps increased b y the great
variability o f some species, and the uncertainty o f the characters
relied upon b y various authors for the purpose o f specific distinction.
No group of plants is more clearly defined in structure, in
general family likeness, and in the localities in which the y are
found, for all are essentially Bog-mosses; y e t as various true mosses
are equally inhabitants of bogs, e. g. various Hypna, Aulacomnium
palustre, Paludella, Meesea, &c., I prefer to term them more
definitely Peat-mosses, since on them alone the first formation o f
peat largely depends, and the name accords with that long recognized
by the Germans, whose Laubmoose or frondose mosses,
Torfmoose or Peat-mosses, and Lebermoose, Livermosses or
Hepaticse, thus form one great Muscal alliance.
F ew persons can have traversed our moorlands without having
had their attention attracted to the great masses o f Sphagnum
which adorn their surface— now in dense cushions o f live ly red—
now covering some shallow pool with a vast sheet o f light green,
inviting it may be by its bright colour, but woe betide the inexperienced
collector who sets foot thereon, for the spongy mass
may be many feet in depth, and he may run the chance o f never
reaching terra firm a again.
T h e plants always grow in this aggregated fashion, for the
stems are weak and fragile, and they thus afford each other
mutual sup po rt; and this fragility requires us to deal gently with
our collections if we would have good herbarium specimens; the
immense quantity of water they retain must be squeezed out
carefully, and not b y roughly grasping the tufts in the hand, otherwise
the stems are sure to be b ro k en ; quick transference to the
press, and a frequent change o f drying paper, will usually ensure a
satisfactory result.
W e may point out to the tyro a few other characters by which
our plants are distinguished from the true mosses. I f we examine
a single stem we find that the branches are in fascicles or clusters,
i. e. spring several together from one point, and at the top are
closely packed in a roundish head or com a ; if we look at the
leaves o f one o f these branches under the microscope, we find they
consist o f a network o f large empty cells which contain threads
winding spirally round on the interior o f the membrane, and are
bounded by a dark line o f narrow cells filled with chlorophyl; the
capsule also is sessile on the dilated end o f a naked branch. F o r
the determination o f species, however, a more minute examination
is necessary, as besides the form o f the various leaves we also
require a knowledge o f their internal structure, as well as that o f
the stem ; this is obtained b y transverse sections o f them, sufficiently
thin to allow the light to be transmitted, and these are
best examined in water and uncovered.
T h e simplest mode of making the sections is to enclose the
wet stem or branches in a split vial cork and tie them tight, then
with a razor to make ve ry thin slices o f the whole, placing them
in a few drops o f water on a slide, when they will immediately
expand and the cork may be picked out with a needle. Russow
recommends that the whole plant be soaked in thick mucilage and
allowed to dry, and then cut with a razor into water. Certain
reagents are also o f use in the examination o f cell structure, as
iodine and sulphuric acid, or a solution o f biniodide of zinc, by the
action o f which the Sphagnum le a f is coloured blue or reddish,
and all its details o f structure sharply defined. Heating the leaves
on a slide in a little liquor sodae is o f value in enabling us to obtain
a clear view o f the outline and condition o f the walls o f cells.
F o r those who have time and the necessary skill, the various
parts may be mounted permanently on slides in glycerine, or other
fluid suitable for vegetable tissues, and they then form ve ry useful
objects for comparison with any specimens which may be the
subject o f examination.* F o r the herbarium, it is better to
separate the tufts into thin layers before submitting them to
* The Rev. Mr. Vize, of Forden Vicarage, Welshpool, has put up sets of the
British Sphagna mounted in this manner.