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60
en Mængde Sidegrene til Tarmen, hvortil det er bundet
ved Bindevæv.
" Imellem Ryg- og Bugkarret er i Tarmvæggene et
intermediært Karnet, hvorved de anastömosere med
hinanden. Hvor disse to Hovedkar tage deres Udspring, der
dannes af de yderst line Kar, hvormed de tog deres
Begyndelse, et Karkomplexus, som omgiver Tarmen. Fra dette
Karnet synes at udgaa Mavens saavel Rvg- som Bugkar.
Vi sige synes; thi saa har det forekommet os paa de
Præparater. vi have havt til vor Raadighed, omendskjønt dette
ikke stemmer overens med Sempers Angivelser, der «tøtte
sig til flere vellykkede Injectioner, og som gaa ud paa at
bevise, at der ingen direkte Forbindelse er imellem Mavens
og Tarmens Blodkar.
Rygkarret er temmelig tint, men bliver tykkere opimod
Ringkanalen, hvor det afgiver en Gren til denne, efterat
det tidligere har sendt flere Grene til Kjønsorganerne.
Fra Rygkarret udgaar en Mængde Tvergrene, som
forbindes med korte perpendikulære Smaagrene, hvorved et smukt
Maskenet med store aflange paatversliggende Masker
fremkommer.
Bugkarret forholder sig ganske paa lignende Maade,
og danner ligeledes et stormasket Net. der anastomoserer
med Rygkarrets, saa at Maven er omspændt af et rigt
Karnet, Tab. VII. Fig. 8, i. Hvorvidt Karret til
Ringkanalen gaar ind i denne, saa at Blodet blander sig med
dens Indhold, kunne vi ikke afgjøre.
Fra de forreste Ender af Mavens Ryg- og Bugkar
danner sig en rig Karfletning, der ligger under Ringkanalen
og omgiver Svælget; det er dette Karplexus, som Semper
kalder Svælgkruset. Denne ringformige Karfletning
udsender en Mængde baade op- og nedstigende Grene til Svælget,
hvor de danne et udbredt Karnet. Desforuden forsyner
den Stenkanalen og den Poliske Blære med Kar.
Nervesystemet.
Nerveringen ligger tæt under Mundskivens Hud,
indenfor Kalkringen, og omgiver Svælget, bundet til dette
ved tynde Bindevævstraade. Den er temmelig bred,
omtrent dobbelt saa bred, som hver af de 5 fra den udgaaende
Radialnerver, og har en straagul Farve. Den dannes af
et ydre beilet Lag (Skeden) og et indre, som er mere
kompakt, og hvori ingen Celler var at opdage. Fra
Nerveringen udgaa mange fine Grene, saavel til Svælget som til
Mundskivens Hud og til Tentaklerne, samt 5 store Grene,
der danne Radialnerverne. Disse ere ved deres Udspring
the extremity of the rectum. It diminishes considerably
in thickness on the inferior descending portion of the
intestine, fig. 3, i, but sends off a large number of
subsidiary branches to the intestine, to which it is webbed by
connective tissue.
Between the dorsal and the ventral vessels, in the
walls of the intestine, extends an intermediary vascular
network, whereby the said vessels are made to anastomose one with
the other. Where these two vessels have their origin, the
minute vessels from which they issue constitute a vascular
plexus, surrounding the intestine. In this vascular
network originate apparently the dorsal and ventral vessels of
the stomach. We say apparently ; for so it seemed to us
when examining the prepared specimens on which our
observations were made, though such an assumption does
not agree with Semper’s statement, which is based on the
result of divers successful injections, undertaken to prove
that no direct connexion exists between the blood-vessels
of the stomach and those of the intestine.
The dorsal vessel is rather slender, but increases
in thickness near the annular canal, whence a branch
proceeds to the latter, several ramifications having been
previously sent off to the generative organs. From the dorsal
vessel proceed numbers of transversal branches, interlaced
with short perpendicular branchlets. thus producing a
graceful network, with large, elliptic-shaped, transversely
arranged meshes.
The same applies to the ventral vessel, which also
forms a wide-meshed net, anastomosing with that of the
dorsal vessel, so that the stomach is completely invested
with vascular network, Pl. VII, fig. 8, i. Whether the
vessel proceeding to the annular canal open into that organ,
enabling the blood to mingle with its contents, we could
not determine.
From the anterior extremities of the dorsal and
ventral vessels of the stomach, a vascular plexus, surrounding
the oesophagus, extends under the annular canal; to this
vascular network it is, that Semper has given the name of
•’pharyngeal curl." This annular plexus of vessels sends off
large numbers of ascending and descending branches to the
oesophagus, where they constitute an extensive vascular
network. It furnishes, too, the sand-canal and the vesicle
of Poli with vessels.
Nervous System.
The nervous ring is placed immediately beneath the
muscular tunic of the oral disk, within the calcareous ring,
and surrounds the oesophagus, to which it is webbed by
slender filaments of connective tissue. It is rather broad,
— about twice as broad as the 5 radial nerves
proceeding from it, and is of a light straw-colour. It consists
of an outer cellular layer (the sheath) and of an inner
layer, more compact in texture, in which no cells could
be detected. From the nervous ring proceed numerous
slender branches, not only to the oesophagus, but also
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