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Svælget. Fig. 6, b, er yderst trangt, knapt 2mm i
Gjennemsnit, har en straagul Farve, løber i Bugtninger
fra Høire Jål Venstre, og er bunden saavel paa Ryg- som
Bugsiden ved et Mesenterium til Kropsvæggen.
Svælgets Vægge ere tykke og dannes af et indre
Epi-thellag (Slimhud), der er’ tykt, bestaar af et Lag lange
Cylinderceller, Fig. 7, a, der paa den indadvendte Ende synes
at være forsynede med Cilier. Denne Slimhud gjør dybe,
regelmæssige Indsynkninger, Fig. 7, b,. b, i det
tilgrænd-sende fibrillære, meget kjernerige Bindevæv, Fig. 7, c}
saaledes nemlig, at derved fremkommer ringformige
Fordybninger, hvilke give Spiserøret paa dets ydre Flade et ringet
Udseende, noget lig en Trachea hos de høiere Dyr, Fig.
6, c. I Bunden af Slimhudsindsynkningerne er
Epithel-laget tykkere end paa Siderne. Til dette fibrillære
Bindevæv fæster sig udad Muskelhuden, der bestaar af
Længdemuskler, Fig. 7. d, der ere de inderste, samt Ringmuskler.
Fig. 7, e, der ere tykkere end hine. Saavel Længde- som
Ringmusklerne anastomosere med hinanden indbyrdes.
Spiserøret gaar nu over i en bredere Del af
Tarmrøret, Fig. 6, c, som paa venstre Side gjør et Par
Bøinin-ger, gaar saa lidt til Høire, Fig. 6, d, løber derpaa
horizontal bag til Kropshulhedens forreste Trediedel, Fig. 6, e,
bøier sig fortil langs venstre Side i en Længde af 12mm,
Fig. 6, /, hvor den ved en Bøining løber lidt paa Skraa
over til høire Side, hvorved den* første Tverslynge opstaar,
Fig. 6, g; her gjør den en let Bøining, løber saa
horizon-talt langs høire Side til omtrent Midten af Kropshulheden,
Fig. 6, h, hvor den danner en anseformig Bøining, Fig. 6, i,
idet’ den gaar over til .venstre Side, hvorved den 2den
Tverslynge fremkommer, Fig. 6, k. Alt hvad der af Tarmrøret
ligger foran den anseformige Bøining og lige til
Mundaab-ningen kalder Lacaze-Duthiers Buccaldelen hos Bonéllia
vi-ridis, idet han ikke som Schmarda differentierer
Mundhulhed og Spiserør fra’ det øvrige Tarmrør. .
I anatomisk-histologisk Henseende er Tarmrøret’ fra
Svælget til den anden Tverslynge ikke \j£sentlig forskjellig
fra Spiserøret; det er noget videre og Væggene noget
tyndere.
Den anden Tverslynge, naar den er kommen over til
Venstre, gjør en Bøining og løber saa over til Høire,
hvorved 3die Tverslynge opstaar, Fig. 6, l; her danner den en
stor Anse for at gaa stærkt pajiskraa over til Venstre: den
4de Tverslynge, Fig. 6, n, hvor den bliver noget smalere
og bøier sig atter for at komme over paa høire Side,
hvorved den 5te Tverslynge, Fig. 6, o, dannes.
De 4 sidste Tverslynger svarer til Lacaze-Duthiers
Leverdel hos Bonéllia viridis. De ere i
anatomisk-histologisk Henseende noget forskjellige fra det øvrige Tarmrør,
idet Væggene ere tyndere; Epithellagets (Slimhudens) Ind-
The gullet, fig. 6, b, is exceedingly narrow, hardly
2 mm jn diameter, straw-coloured, winds from right to left,
and is webbed, both on the- dorsal and the ventral side, to
the wall of the body by a mesentery.
The pharyngeal walls are thick, and consist of an
inner layer of epithelium (mucous integument), which is
also thick; it consists of a layer of long cylindrical cells,
fig. 7, a, furnished apparently, on the side turning inwards,
with vibratile cilia. This mucous skin corrugates the
fibril-lous, nucleal tissue adjacent, fig. 7, c, with a number
of deep, regular troughs, fig. 7, b, b’, in such wise as
to produce annular depressions, which give to the outer
surface of the oesophagus an annulated appearance, not unlike that
of the trachea in more highly organised animals, fig. 6, c.
At the bottom of the troughs in the mucous skin, the
epithelial layer is thicker than at the sides. To this fibrillous
connective tissue, is webbed from without the muscular
integument, composed of longitudinal muscles, fig. 7, d, — the
innermost layer, — and of annular muscles, fig. 7, e,
somewhat thicker than the former. Both the longitudinal and
annular, muscles anastomose reciprocally.
The oesophagus now opens into the broader portion of the
intestinal canal, fig. 6, c, which, on the left side, makes a
twist or two, passes a little to the right, fig. 6, d,
protends from thence horizontally back to the anterior third
of the perivisceral cavity, fig. 6, e, winds forwards along
the left side for about 12mm, fig. 6, f, where, after making
a twist, it takes a’ somewhat oblique direction across to
the right, thus completing the 1st transverse
circumvolution, fig. 6, g. Here it makes a slight twist, protends
horizontally along the right side about to the middle of the
perivisceral cavity, fig. 6, h, where, after making an
ansi-form twist, fig. 6, i, it passes across to the left side, and
terminates the 2nd transverse circumvolution, fig. 6, k.
The whole of the intestinal canal extending forwards from
the ansiform twist to the oral aperture, Lacaze-Duthiers
terms the buccal region, that naturalist not having, like
Schmarda, distinguished the oral cavity and the oesophagus
from the remainder of the intestinal canal. *
As regards its anatomical-histological structure, the
section of the intestinal canal extending between the gullet
and the second • transverse circumvolution, does not differ
materially from the oesophagus, being merely a little wider,
and with somewhat thinner walls.
On reaching the left side, the second transverse
circumvolution makes a twist, and then passes across to the
right side, thus producing the 3rd transverse
circumvolution, fig. 6, I. At this point it protends, with a wide
bend, very obliquely across to the left side (4th
transverse circumvolution, fig. 6, n,), where its thickness has
slightly diminished. It now makes another twist, across
to the right side, and forms the 5th transverse
circumvolution, fig. 6, o.
The 4 last transverse circumvolutions represent the
liver-section in Bonéllia viridis, according to
Lacaze-Du-thiers. Their anatomical-histological structure differs
somewhat from that distinguishing the remainder of the intestinal
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