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constituted o f three distinct cell formations, viz. a central pith,
an intermediate woody cylinder, and an external bark, though,
o f course, these cannot correspond to the parts so named in higher
plants ; it seems, however, more appropriate to regard, the stem
o f Sphagnum as consisting o f a cylinder, the cells o f which are
soft and succulent in the centre, but become indurated and
coloured as they approach the exterior, and an investing cuticle
composed o f one to four strata o f large, thin, empty cells, not
inaptly compared by Lindberg to the velamen or spongy cuticle
investing the roots o f epiphytal orchids, which also consists of
large aeriferous cells.
T h e cells o f the axis are long and cylindric, with thin colourless
walls, and allow the sap to pass freely up to the growing
point ; those o f the periphery are narrower, prismatic, and more
or less lignified b y internal deposit on their walls; their colour
also varies according to the species, and we thus observe them
in a transverse section o f the stem, forming a yellow, brown, red,
or blackish ring lying immediately under the cuticle ; and it is to
the colour o f these cells appearing through the transparent cuticle
that the tint o f the fresh Sphagnum stem is due.
T h e cuticular cells are the largest, and instead o f receiving
any deposit they become thinner b y a g e ; they are also empty,
and in some species contain fine spiral threads on their internal
wall ; they are also frequently perforated by foramina, by which
they readily communicate with each other.
T he B r anches.
T h e branches spring from the growing cone immediately after
the leaves, in the form o f a little obtuse bud at the side o f every
fourth le a f; and when this has attained a height o f three cells,
the rudiments o f the branch leaves also protrude themselves at
the outer side.
T h e distinction between the central and peripheral cells o f
the branches is much less complete than in the stem, and the
cuticular cells only form a single stratum, which is continuous
with the innermost layer o f the stem cuticle when this consists
o f more than one stratum. T h e cuticular cells o f the branches
are o f two forms, as may be readily seen if we strip off the leaves,
viz. large transparent parenchym cells like those o f the stem
cuticle, and still larger flask-shaped or retort cells, more or less
ventricose at base, and gradually contracted upward into a more
or less distinct, somewhat arched neck, which is perforated by a
foramen at apex ; they are v e ry distinct in Sphagnum tenellum,
but in some species the neck is scarcely evident; one o f these
retort cells always falls at a lea f insertion, and they never contain
spiral threads, even when these are present in the ordinary cells
of the branch cuticle.
In most species o f Sphagnum the branches which constitute
each fascicle are of two forms ; part o f them stouter and directed
outwards from their insertion, become arched at the middle and
gently curve downward at the extremity, and these may be called
the divergent bran che s; the rest are longer and more attenuated,
with longer and narrower leaves, hang straight down, and are
often closely appressed to the s tem ; these we term the pendent
branches, and the number and direction o f each o f these in a
fascicle is pretty constant in each species.
T h e branches always stand close to a leaf, at the end o f its
line o f insertion on the stem, and at every fourth leaf a branch
fascicle is found, their arrangement being in five straight rows, with
the formula f , i. e. three complete turns o f a spiral contain five
fascicles.
Some o f the uppermost divergent branches become condensed
and clavate, and form the amentula o f male inflorescence.
It is by means o f the pendent branches and cuticle o f the stem
that the wonderful hydraulic property o f the Sphagna is maintained,
and this is readily seen if we place an uninjured stem in a
glass o f water and allow the top to hang over the margin, for the
water rises by this channel, and soon begins to drip from the
drooping end, until, like a syphon, it has drawn off all the contents.
Not only do the Sphagna thus give off water to the atmosphere,
but the y can on the other hand also absorb moisture from it and
transmit it downward ; in this way a constant interchange goes on
between the stagnant pools and the atmosphere, by which means
no doubt the former are prevented from becoming putrid.
T he L eaves.
Hofmeister admirably describes the development o f the leaves
of Sphagnum; they arise from the outer cell layer o f the growing
point, the first lea f cell appearing from the second, third, or fourth
cell below the terminal one, and this dividing repeatedly by alter