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41
Dr. Lindahl har givet en schematisk Fremstilling af
Polypernes Anordning, saaledes som lian har tænkt sig
den foregaar. Den er kun en Hypothese; thi nogen direkte
Iagttagelse over Polypernes Udvikling og Stilling paa
Rachis foreligger ikke. Efter hvad vi have observeret paa
vore 12 Exemplarer, foregaar ikke Polypernes Frembrud
paa den af ham tænkte Maade. Vi ere fuldstændig enige
med ham deri, at Torniiiialpolypeii er den förste, som
bryder ud af Rachis; men stort længere strækker heller ikke
Enigheden sig. Naar Terniinalpolypeii er dannet, mener
Lindahl, at nedenfor denne fremkommer en ny Polyp, som
han betegner "Basalpolyp", saalænge den beholder denne
Plads. Han siger fremdeles: "Undertiden har han ändrat
plats och blifvit lateral polyp, idet han stält sig vid venstra
sidan af terminalpolypon, undantrængd af en ny, i tilväxt
stadd polyp, hvilken intagit den forres plats som basalpolyp
i inidtellinien af rachis, och i sin ordning växer fatt sina
hilda föregångare och drager sig åt andra (högra) sidan
om terniinalpolypeii". Af det foreliggende Material
udbryder de laterale Polyper efter Endepolypens Dannelse
uden nogen saadan Vandring, som Lindahl antyder, og
efterat ft Par laterale Polyper ere fremkomne paa hver
Side. udvoxer Rachis i Bredden, hvorpaa de ceiitral-dorsale
og senere de dorsal-laterale Polyper udvikle sig
efterhaanden. ligesom de laterale Polyper tiltage i Antal, l’dvikligen
af Rachis og det Rum, som derved vindes, synes at være
det Bestemmende for Polypernes Anordning; men forovrigt
kan intet sikkert herom siges, førend man har en langt
større og mere sammensluttende Række af Exemplarer,
end vi have havt.
Vi skulle nu gaa over til at fremstille den indre
Bygning af Umbéllula encrinus.
Dr. Lindahl has given an outline representation ol
the development of the polyps, as he has supposed it to
proceed. This is only a hypothesis, however, because it is
based on 110 direct observation of the development and
arrangement of the polyps on the rachis. From what we
have observed in our 12 specimens, the first appearance
of the polyps does not occur in the manner lie has
supposed. We quite agree with liim in this; that the terminal
polyp is the first one which springs from the rachis, but
the unanimity does not proceed much further. When the
terminal polyp is formed, Lindahl thinks, that below it, a new
polyp appears, which be designates "basal polyp" so long as
it retains that position. He states further: "Sometimes it
has shifted position and become a lateral polyp, and becomes
situated at the left side of the terminal polyp, forced out
by a new polyp in a state of growth, that has occupied
the situation of the first, as basal polyp in the mesial
line of the rachis, and in it’s arrangement grows away from
both its predecessors, and places itself at the other side
(right) of the terminal polyp". From observation of our
material, we find that the lateral polyps appear after the
formation of the terminal polyp, without any such travel
as Lindahl indicates, and after a couple of lateral polyps
have appeared 011 each side, the rachis expands in breadth,
and then the centro-dorsal. and, subsequently, the
dorsolateral polyps, develope themselves, gradually, whilst, also,
the lateral polyps become more numerous. The
development of the rachis, and the space which is thereby obtained,
seems to be the regulating moment in the arrangement
and development of the polyps; but, nothing certain,
however, can he said as to this, before a much larger
and more continuous series of specimens is obtained, than
we have had.
We shall now proceed to discuss the inner structure
ol’ Umbéllula encrinus.
Den anatom islc-li i stol og i ske Bygning.
De 4 store Længdekanaler, der .gjennemløbe hele
Stokken, undergaa. Forandringer \;osontligt. eftersom
Axo-dreiningerne foregaa. Paa Midten af Stokken ere Kanalerne
næsten lige vide; Ventral- og Dorsalkaualen er dog lidt
større i Omfang end Sidekanalerne, og lier ligger Axon i
Centrum. Lam gere op imod den skedeformige Udvidning,
hvor Axon nærmer sig Ventralfladen, begynder samtlige
Lamgdekanaler at. fordreie sig noget, hvilken Fordreining
bliver endnu stærkore i den skedeformige Udvidning og i
selve Rachis. Vi maa henvise lil de to Tvorsnit. Tab.
VIII. Fig. 30 og 31. for at gjøre det ret forstaaelig^ Dot
forsti- Tvorsnit, Fig. 30, or foretaget omtrent midt paa den
skedeformige Udvidning, og her viser det sig, at Axon or
skudt holt hen til Ventralsiden, Fig. 30, a; Vontralkanalen
er ligesom dreiet og udvidet mod Sidekanalen, Fig. 30, b.
Den lløire Sidekanal er t rukken mod Dorsalkaualen og temmelig
udvidet imod Coonenchymvæggen, Fig. 30, c. Dorsalkaualen
I>■.*11 norske Xorrilmvscxperiition. Diiiiiolssou og Koroii. I’onnatulicln.
The anatomo-histological Structure.
The 4 large longitudinal canals which extend through
the whole of the stalk, undergo changes, more particularly,
according, as the twistings of the axis occur. In the
middle of the stem, the canals are almost uniform in width;
the ventral and dorsal canals are, however, a little greater
in size than the lateral canals, and here, the axis lies in
the centre. Further up, towards the sheath-formed
dilation. where the axis approaches the ventral surface; all
the longitudinal canals commence to twist themselves a
little, and the twisting becomes still greater in the sheath
formed dilation, and also in the rachis itself. We must
refer to the two sectional illustrations (Pl. VIII, fig. 30
and 31) to make our description more intelligible. The
first section (fig. 30) illustrates the situation about the
middle of the sheath-formed dilation, and, here, it is seen,
that the axis is pushed quite aside to the ventral side
(fig. 30 a). The ventral canal appears, as if twisted, and dilated
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