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They ai'e roimclish, on ])edicels as long or longer than themselves, generally solitary in the axils of the perigonial
leaves, which are somewhat ventricose at the base, but not othenvise différent from those of the stems.
The anatomy of the theca of Spltagnxm is veiy peculiar. What appears the colmnella does not extend, as in other
genera, to the smmnit of the theca, but is a continuation of the seminal sac, ascending from the bottom of the theca,
and fonus a portion of the same membrane wliich also lines the imder sm-face of the opercidiim, passing completely
across the stoma, as sheum in Plate LA'IL fig. A"I., where the central figm-e is di-awn from a sketch and section prepared
by JIi-. Wilson.
This cmious stmcture of the seminal sac is quite different from what obtains in most genera of mosses, and
appeal's to have been mismiderstood by iVi-nott and Greville, in whose excellent essays upon the ‘ Genera of Mosses,'
the colmnella is described as sinking, along with its opercular membrane, so low, as to assume the appearance of a
tympanum, stretched across the interior of the theca, a little below its base (Weru. Trans, vol. iv. p. 131.); tliek figme
hoAvever does not represent the colmnella bearing any residua of tbe opercular membrane, but merely having the base
of the seminal sac di-aAATi up into the axis of the theca in the form of a cone, Avhich is its true origin. The more
striking pecidiai-ities of the spondai* sac of Sphagmt-m ai-e these ; 1st. its forming a bag or cyst Avithout any orifice ;
2nd, in the ibaAving up of tbe base of this bag into the axis of the theca, but not so far as to reach tbe level of tbe
stoma, nor consequently tbe upper smface, or tbat opposite the base, which remains entbe and stretched across the
stoma. If the cohmiella were caiTied up to the same height as in other mosses, an obhteration of the upper part of
the sponilar membrane Avould be caused by the peiforatiou of the latter, (if we regard themetula as a portion of the
columella), or else there Avoidd ensue a mutual cohesion of the membranes of columella and sac.
SpJiagmm may be considered to possess the simplest foi-m of sporular sac, the dehiscence of Avhicli is probably
caused by a removal of the upper portion in the same plane as the stoma and parallel to the opercidmn. The next
stage of development of this organ is, perhaps, presented in some astomatous mosses; Voitia'*, for instance, a perpendicular
section of the theca in Avhich genus exhibits the seminal sac in the form of a vertically elongated ring,
supported in the axis of the theca by the corcidum of the columella. The latter passes uninteiTuptedly from the
apex of the seta to the top of the persistent opercidum, thus apparently perforating the sac, by Avhose inflected AvaUs
it is hned for the greater pai't of its length. In this case, dehiscence aud the escape o f the spbrules may be supposed
* In tbe young state of Voitia hyperhorea, of Avhich (thi-ough the kindness of Sh* James Ross), I have examined
many thecæ, there is a communication between the seminal sac and the lining of the Avails of the theca (thecal
membrane), by means of confen'a-like filaments such as are seen in most other mosses. Tracing the different
membranes upwards, fr-om the apex of the theca, I was led to believe that the same tissue formed the thecal membrane,
the confeiwa-hke filaments, and the corculmn of the columella; and fin-ther, the immediate communication
between all the surfaces of the seminal sac and the waRs of the theca afforded room for a conjectiu-e, that the latter
were immediately concerned in the development of the sporules, especially as before the separation of the spores
both the thecal membranes and filaments Avere fidl of a grumous fluid, which afterwai-ds disappears. If such a vicAv
be con-ect, the internal structure of the theca of Voitia is very simple, and consists, 1st, of stout cells foi-ming the
extei-ual walls ; 2nd, of a fine tissue, not oidy lining the former and sending filaments to the opposite AvaUs of the
seminal sac, but, becoming more condensed at the base and apex of the cavity of the theca, it ascends in its axis and
meets the descending portion in the hoUoAv of the columella, over Avhose sm-faces they both ramify ; and 3rd, of a
vertically elongated ring (the seminal sac) through Avhose centre tins second membrane passes. Mi-. Yllson (to
whom I am indebted for my knoAvledge of tbe stmctm-e of both theca and ceRular tissue of SpJiaymm), has not been
able, from the Avant of specimens, to confirm this -view of the stractm-e of Voitia; he, hoAvcvcr, informs me, that
“ the existence of such a connecting tissue is only analogous to Avhat is fouud in Gyninostomxm pijriforme, whose
spondar sac is connected with the base of the theca by a bundle of filaments ;” he also adds, that “ in many Pohj-
tricha there is a distinct, almost woody, central axis to the columella, Avith filaments iiitervening betwixt it and the
AAunged folds of the spondar sac Avliich fom s the outer part of the columella.”—J. D. H.
to take place through the decay of the theca, when, as frequently happens, the theca and seta are together detached
from the plant, and possibly, if persisLeut, the operation may be aided by the developmeut of a fungus Avhich we
have seen in the Avails of the capsule of V. hyperhorea.
The more complicated structm-e of these parts, which most peristomed mosses possess, may eventually prove
mere modifications of, or dcAuations from the simpler organization of Voitia and Sphagnum. Gymnostomwn pyriforme
tends to confirm such a theory; in it the columella (what is considered as such being the inflected portion of the
sac), ascends from the bottom of the theca to the le\'el of the stoma, and then, expanding outiA'ards, Hke the
mouth of a funnel, reunites Avith the seminal sac around the rim of the stoma (vid. Grev. and Am. 1. c. vol. p. — ).
Aft er a time, the edge of the funnel breaks away from that of the sac and ivith the columella shrivels up, thus giAung
egi-ess to the sporules.
Mr. Valentine, in his ‘ Genera of Mosses,’ has aecm-ately described tbe cellular tissue of Sphagnum, which is,
in several respects, exceedingly cm*ious. The cells themselves are bounded by very thick lines, formed of slender
tubes, rumiing between the contiguous cells, but on one side of the leaf only; a transverse section of a small portion
of a leaf, exliibiting both the cells and the interjected tubes, is shoAvn at fig. 46. A^alentine considers that the
latter are derived fr-om the elongated tubes of the stem.
The cells themselves are fm-nished, in some foi'ms of the genus, AAuth one or more spiral filaments, closely adhering
to then- walls, sometimes these are entii-e thi-oughout the length of the cell, at others broken or both broken
and branched. We ai-e inclined to believe that the spiral filament is terete and adlicres by a small portion only of
its sui-face to the tissue of the leaf; the extreme minuteness and transparency of the parts, however, increase the
difficulty of determining such a point with the accm-acy that is desirable. No function has, hitherto, that Ave are
aAvare of, been assigned to these filaments; they may act powerfully in enabling so delicate a tissue to Avithstand tbe
pressure of the water.
The pores, by means of which a communication between the cavity of the cells and their sui-roimding medium
is preserved, are, in most cases, numerous aud large, iu others less s o ; they appear more frequent on the upper surface
of the leaf, but are by no means confined to it, for sometimes they are placed opposite to one another, when the
leaf itself is perforated. They exist both in cells provided Arith spiral filaments and Avithout; in some instances,
Avhere the spires are broken and branched, the pores are bordered Arith a thick ring given off fi-om the filament,
Avhence probably arises the supposition that Avhat appeared to be pores Avere supplementai-y coils. They varj'
greatly in size, occasionally extending completely across the cell. Yalcutine describes them as resembling a minute
truncated cone ; to us they appeal* on the same plane with the walls of the cells, except where then* edges are thickened,
as described above. In S. mao'ophyllum the cells are devoid of any filaments, are very naiTOAv, much elongated,
and each perforated by from 8 to 14 large pores, A\-liich sometimes nearij' diA-ide the cell on one sid e ; they ai-e
by fai- most numerous on the upper sm-face of the leaf. The uses of these pores ai-e hitherto unknomi, they may
be due to the nature of the situations iu Avliich the species are fouud. We have not proA-ed them to reside iu the
intercellular tubes, tbough tbeir existence in theii- AvaUs is possible also. On the other hand, the latter alone may
continue rcservoii-s for Avater during dry seasons, when, from the porous nature of the former, they readily part Avith
theii- moisture.
Until the dehiscence of the operculmn, no ruptm-e of the calyptra takes place iu Sphagnum. AVe haA'e not observed
the desiliciit property of the operculiun, noticed by some authors. The sponilcs iu all the species ai-e clustered
together in fours, of Avhich three only are generally Adsibie at first siglit, as represented at Fig. \ l . In most of the
species tlie surface of the theca is studded over Avitli stomatiform pores; these are however very inconspicuous, if
not Avliolly absent, iu S. cymhifoUum. The true pedicel is included Avitliin the vaginula and is singidai-ly dilated be-
loAV the orifice of the latter.
P l.a te LA""!!. Fig. A’’!.—1, Longitudinal section of theca of S. cymhifoUum; 3, section of cellular substance
from centre of the same; 3, spores in a very youug state; 4, cellular tissue of leaf shoAving spiral vessels and pores ;
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