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19
Professor Ehlers har i det nys citerede .Tidsskrift
leveret • en særdeles god monographisk Bearbeidelse af
Slægten Priapidus, hvortil Priapuloides i mange Henseender
slutter sig. Vore histologiske Undersøgelser over begge
disse Slægter have i enkelte Punkter ledet til Resultater,
der ere noget forskjellige fra dem, Ehlers er kommen til
over Priapulus, og om end Afvigelserne ikke ere meget
store, skulle vi dog fremhæve dem.
Ved Huden omtaler Ehlers et subcuticulart Lag, der
ligger indenfor Chitinlaget, og som efter ham bestaar af et
finkornet Lag, hvori ingen Celler tydelig- kuntle’ sees, og
som ligger imellem Ringmusklerne og Chitinhuden. Vi have
fundet constant et temmelig udpræget Epithellag indenfor
Chitinhuden, bestaaende af .Cylinderceller; dette Epithellag
er fæstet til et stærkt Bindevævslag, hvortil Muskelhuden
er bunden. Det synes, som ’om Prof. Ehlers ganske har
overseet dette Bindevævslag, hvis ikke han hai- antaget det
finkornede Subcuticularlag derfor.
De. paa Snabelens ydre-Flade siddende Pigge ere
omgivne af en Skede, Fig. 11, a, 12, a, der er en
Forlængelse af Chitinhuden; kun er Skeden kortere hos Priapulus
end hos Priapuloides. Den hule Pig har i Spidsen en
Aabning, Fig. 11. 6, 12, 6, og er indvendig beklædt med
et Epithel, Fig. 11. c, Continuation af Hudens Epithellag,
ligesom der ved Grunden af Piggen er en Kjertel med sin
Udførselsgang,- Fig. 11, d. Elilers omtaler hverken Skeden
eller Kjertelen, ei heller Aabningén i Piggens Ende,
hvorigjennem Kjertelsekretet udføres.
Cuticula (Chitinlaget) er hos Priapidoides tæt besat
med koniske Chitinpapiller, imedens den hos Priapidus er
glat.
Folderne paa Tarmrørets indre Flade dannes af
fremspringende Bindevævslister, hvortil Epithelet er fæstet.
Dette bestaar af meget lange Cylinderceller, der
sandsynligvis ere forsynede med Cilier. Imellem Cylindercellerne
saaes særegne Celler, som vi have antaget for Slimkj ertier.
Ehlers angiver, at den indre Flade af Tarmen paa
Priapidus har et Chitinovertræk, der efter ham skal være en
Fortsættelse af den ydre Huds Chitinlag, og at dette
Chitinovertræk ikke alene danner Tarmfolderne; men at det i
den midterste Tarmdel er forsynet med lange, stive
Chi-tinhaar.
Vi have tidligere angivet, at vi paa Tarmens indre
Flade af et Exemplar af Priapuloides, ligesom vi ogsaa paa
et Exemplar af Priapidus saa noget, der kunde antages for
en tynd Chitinhud med de nævnte Haar; men det riste sig
ved nærmere Undersøgelse at være et Overtræk dannet af
coaguleret Slim. De Cilier, vi have iagttaget paa
Tarm-epithelet, vare indenfor den omtalte og af Ehlers antagne
Chitinhud, hvilket end mere bestyrker os i, at denne ikke
kan være andet end en Tilfældighed.
Professor Ehlers has lately furnished, in the Journal
cited above, a most excellent monographic review of the
genus Pnapulus, with which Priapuloides in many respects
is found to congrue. Our histological investigation of both
genera has been attended with results deviating slightly in
certain points from those of Elilers for Priapulus; and
though the difference is not considerable, it will be well
to point out wherein the observations , that-have led to it
diverge.
Professor Elders describes a subcuticular layer in’the
skin, underlying the chitinous layer, and which consists of
a finely granulous stratum — in which no cells could be
readily distinguished — extending between the annular
muscles and the chitinous cuticle. We have found, as a
constant feature, underneath the chitinous integument a
comparatively well developed epithelial layer, consisting of
cylindrical cells; this epithelial layer is attached to a layer
of strong connective tissue, webbed to the muscular
integument. Professor Ehlers would appear to have overlooked
altogether this layer of’ connective tissue, unless indeed it is
this which he terms the finely granulous subcuticular layer.
The spikes on the outer surface of the’ proboscis are
enclosed in a sheath, figs. 11, a; 12, a, — the chitinous
integument produced; but the sheath is shorter in
Priapidus than in Pnapidoides. The hollow spikes have each
an aperture at the point, figs. 11, b; 12, b, and are
invested on the inner surface with epithelium, fig. 11, c, —a
continuation of the epithelial layer of the skin; and
moreover, there is at the base, of every spike a gland, furnished
with an excretory duct, fig. 11, d.. Ehlers mentions neither
the sheath, the gland, nor the aperture at the pointed
extremity of the spike through which exudes the glandulous
secretion.
The cuticle (chitinous layer) in Priapidoides is
densely studded with conical chitinous papillæ, whereas it is
smooth in Priapidus.
The folds on the inner surface of the intestinal
canal consist of prominent membranous fillets, attached to
the epithelium. The latter consists of’ exceedingly large
cylindrical cells, -furnished probably with vibratile "cilia.
Between the cylindrical cells were seen other cells,
possibly mucous glands. According to Ehlers, the inner
surface of the intestine in Priapulus is invested with a
chitinous tunic, a continuation, as he. conceives, of the chitinous
layer in the outer integument; and in his opinion, this
chitinous tunic not only produces the folds of the intestine,
but is furnished on the medial portion of the latter with
long, bristly chitinous capillaments.
We have previously stated, that we, too, detected
on the inner surface of the intestine in a-specimen of
Pnapidoides, and also in a specimen of Priapulus, what might
be taken for a thin ch’itinous skin, bearing such
capillaments; but, on closer examination, it proved to be
coagulated mucus. The cilia we have observed on the
intestinal epithelium, occurred underneath Ehlers’ supposed
chitinous integument, a circumstance affording additional
proof of the feature in question being strictly casual.
3*
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