C H A P T E R H I .
T H E V E G E T A T I V E S Y S T E M .
G ermination of th e S pore.
T o the investigations o f Nägeli and Hofmeister are we principally
indebted for our knowledge o f the development o f the plant, and
Professor Schimper further observed them under cultivation, and
found that on damp earth the spores germinated in two to three
months, and that the proembryonal cell rarely broke through the
exospore or outer coat in less than five weeks.
T h e development proceeds under one o f two forms, according
to the local conditions in which the spores may happen to be
placed at the t im e ; thus, if they be immersed in water, the g e rminating
proembryo assumes the form o f a confervoid protonema,
somewhat akin to that o f true mosses, but more elongated and
less bran ched ; from one end o f this the young plant arises b y a
tuberculoid aggregation o f cells, while the other extremity becomes
a root, or one o f the middle cells becomes the mother cell o f the
new plant. But if the spore germinate on the damp ground, the
proembryonal cell goes on subdividing in a horizontal plane, and
the result is a lobed green prothallium like that o f Equisetum, consisting
o f a single layer o f c e lls ; this hepaticine frond throws out
radicles from the under surface and margins o f the lobes, and
quite resembles a plant o f Blasia or Antkoceros. A fte r a while,
cells aggregate here and there at the margins o f the lobes and form
rudimentary plants, which support themselves partly from the
prothallium, partly by rad icle s ; in the plants growing in water
also, the radicles attach themselves to any fixed body, and thus
securely anchor the plants until they are in a condition to take care
o f themselves.
T h e roots in the young plants o f Sphagnum precisely resemble
those of frondose mosses, consisting o f slender elongated cells with
oblique transverse septa, and their functions are also similar, for
they serve both for support and nutrition; as soon, however, as
the branches are produced, a portion o f them become pendent and
appressed to the stem, and these with the spongy cuticle o f the
stem are far more effective than the' roots for the transmission o f
fluid, while the dense masses formed by the aggregation o f stems
equally supersede the necessity for roots as fixing organs ; these,
therefore, being no longer needed, wither away and completely
disappear.
T he S tem.
T h e young stem appears from the under side of the prothallium
by a change in the cell formation, some o f the cells developing
downwards into hair-like radicles, while the upper cell elongates
and subdivides to form the young stemlet, some o f the cells also
becoming free laterally to form the rudimentary leaves ; it is at
first transparent, but soon acquires chlorophyl granules, and a differentiation
into its cell layers is distinguishable at a v e ry early
stage.
When the young stem has attained a height o f 5 mm. it throws
off at the sides simple flagellar branches, which arise laterally to
the uppermost leaves, and are at first crowded in the coma and
separate by elongation o f the internodes. T h e branches come off
at every fourth le a f as an obtuse bud, on which, when it has
attained a height o f three cells, leaves also form and division into
branches takes place.
T h e growing point o f the stem is conical, its terminal cell
apparently subdividing in five directions, and thus continually
elongating the stem ; by longitudinal division and transverse extension
o f newly formed cells, the terminal cone thickens from above
downward, and the base constantly farming anew attains the
diameter o f the already completed stem.
T h e trunk or perfectly developed stem consists o f a simple
primary axis with numerous terminal shoots enclosing the central
terminal bud, and also o f several secondary axes ; for each year a
lateral shoot is formed beneath the growing point, which is an
exact repetition o f the original main stem, with which it keeps a
perfectly parallel advance in growth and development ; in fact, it
is nothing else but one o f the fascicled lateral branches transformed
into an ascending axis, and this again repeats the process the
following season, so that we thus obtain not only the dense dicho-
tomous ramification, but the fastigiate surface so characteristic o f a
cushion o f Sphagnum plants.
Professor Schimper in his great work described the stem as