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24
have nogen Lighed med Føddernes Kalkspikler, men ere
dog lidt forskjellige fra disse i Form. ligesom de ere noget
mindre. Som oftest ere Tentaklernes Spikler forgrenede
snart i den ene, snårt i begge Ender, og synes at være
rigere paa Takker, Fig. 11. Ogsaa i denne Dels indre
Bindevævslag træffer man paa de elliptiske Kalklegemer,
forøvrigt er den histologiske Bygning den samme, som i
Skaftet. Tentaklerne kunne indtrækkes til den bredere Del,
altsaa kun Skaftet kan trækkes ind i Legemet og
Tentakelen paa den Maade forkortes; men ligesom Tilfældet er
med Fødderne, saaledes ogsaa med Tentaklerne; den rige
Spikelbeklædning lægger Hindringer iveien for. at de gauske
kunne skjules i Kropshulheden.
Fordøielsesorganerne tage sin Begyndelse ved
Mund-aabningen, hvor Indgangen til Svælget (Atriet) er temmelig
vid og foldet, meget muskuløs, og bidrager til at danne den
stærke Sphincter omkring Munden. Svælget er meget
snevert, temmelig langt, Fig. 3, b, og bundet til Kalkringen
ved en Mængde muskuløse Traade, ligesom der fra dets
ydre Flade afgaa mange fine Bindevævstraade til
Mundskivens bagerste Flade. Det er beklædt af det flimrende
Peritoneum, indenfor hvilket findes et tyndt Bindevæv,
hvortil Ringmuskellaget er bundet. Umiddelbart paa dette
hvile Længdemusklerne; saavel Ring- som Længdemusklerne
synes ikke at være adskilte i Bundter; men Fibrene løbe
parallel med hverandre, saa det faar Udseende af at være
en sammenhængende Hud. Indenfor Længdemusklerne er
atter et Bindevævslag, hvori sees en rig Karudbredning.
Til dette Bindevævslag fæster sig et tykt Lag af
Cylinder-epithel. der bidrager til at danne de stærkt fremspringende
Længdefolder, hvormed Svælgets indre Flade er forsynet!
Lidt bagenfor Vandkarringen gaar Svælget over i
Maven, der danner en aflang sækformig Udvidning. som er
temmelig muskuløs; men hvis Vægge dog ikke ere saa
tykke, som Svælgets, Fig. 3, c. Paa Mavens indre Flade
findes ligeledes en Mængde Folder, der rage ind i
Hulheden. Saavel Svælget som Maven havde en jævn
brunligrød Farve og våre tomme. Hvor Maven gaar over i
Tarmen er en Indsnøring. Tarmen dreier sig strax mod Venstre,
hvor den gjør en Bøining, gaar saa næsten horizontalt langs
Bugfladen bagover til den bagerste Trediedel af
Kropshulheden. Fig. 3. d; her bøier den sig atter, gaar nu forover
og skraat over til høire Side. næsten i Niveau med første
Slynge, Fig. 3, e, og sender nogle Bindevævsbaand over til
Maven, Fig. 3, f ; herfra gjør den en Bøining, idet den
gaar paany bagover noget paa skraa, Fig. 3, g, indtil den
ved Begyndelsen af Kropshulhedens bagerste Trediedel
danner et Knæ for i Midten af Hulheden at gaa horizontalt
bag mod Anus, Fig. 3. li. Paa denne horizontale Del. der
maa ansees for Rectum, er en temmelig tydelig Udvidning,
lobes, is furnished in great abundance with calcareous
spiculæ. Here, being as it were braided together, they
assume the appearance of an elegant armature, presenting in
other respects some resemblance to those in the suckers,
though slightly different in form, and smaller. The greater
part of the tentacular spiculæ are branched, some at one
extremity, others at both; their dentelli, too, are
apparently more numerous, fig. 11. In this part also occur the
elliptic calcareous corpuscles, distributed through the inner
layer of connective tissue; the histological structure is in
other respects similar to that of the shaft. The tentacles
can be retracted up to their broader part, that is to say.
the shaft alone admits of being withdrawn into the body,
and to that extent accordingly they are contractile; but. as
with the suckers, so with the tentacles, the spicular surface
of the integument prevents their being wholly concealed in
the perivisceral cavity.
The digestive organs originate at the oral aperture,
or rather at the entrance to the gullet (the atrium),
which is rather wide and folded, and exceedingly muscular,
contributing to the formation of the powerful sphincter
surrounding the mouth. The gullet is remarkably narrow,
rather long. fig. 3, h, and webbed to the calcareous ring by
a number of muscular filaments; from its outer surface, too.
numerous slender’ filaments of connective tissue proceed to
the posterior surface of the oral disk. It is covered by
the ciliated peritoneum, beneath which extends a thin
connective membrane, to which is webbed the layer of annular
muscles. Above, and in direct contact with, the latter, are
the longitudinal muscles ; neither the annular nor the
longitudinal muscles would appear to be arranged in fascicles;
but their fibres run parallel to one another, giving the
appearance of a continuous skin. Under the longitudinal muscles
occurs another layer of connective tissue, in which is seen an
extensive vascular arrangement. This layer of connective
tissue is webbed to a thick layer of cylindric, cellular
epithelium. which contributes to the formation of the abruptly
projecting longitudinal folds on the inner surface of the gullet.
A little posterior to the water-vascular ring, the gullet
opens into the stomach, an oblong sac. which is rather
muscular, but with somewhat thinner walls than those
of the gullet, fig. 3. c. On the inner surface of the
stomach occur too a number of folds, projecting into the
cavity. The gullet and the stomach, which are of a
uniform brownish-red. were both empty. At the point
where the stomach opens into the intestine is seen a
constriction. The intestine immediately strikes off to the
left, and then makes a bend, proceeding backwards, and
almost horizontally along the ventral surface, to the
posterior third of the perivisceral cavity, fig. 3. ♂; here it makes
another bend, taking a forward and oblique course to the
right, almost in a plane with the first convolution, fig. 3. e,
a few ligaments of connective tissue now connecting it with
the stomach, fig. 3, f : here it bends anew, and obliquely
backwards. fig.3.♂, continuing in that direction till, at the
commencement of the posterior third of the perivisceral cavity,
it forms a kind of knee, proceeding, when arrived at the
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