Dr. Lindahl har 
Polypernes Anordning, 
den foregaar. 
givet en schematisk Fremstillmg af 
saaledes som han har tænkt sig 
Den er kun en Hypothese; thi nogen direkte 
Tagttagelse over Polypernes Udvikling og Stilling paa Ra- 
ehis foreligger ikke. Efter hvad vi have observeret paa 
vore 12 Hxemplarer, foregaar ikke Polypernes Frembrud 
paa den af ham tænkte Maade. Vi ere fuldstændig enige 
med ham deri, at Terminalpolypen er den første, som bry- 
der ud af Rachis; men stort længere strækker heller ikke 
Enigheden sig. Naar Terminalpolypen 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 åndrat 
plats och blifvit lateral polyp, idet han stålt sig vid venstra 
sidan af terminalpolypen, undantrængd af en ny, 1 tilvåxt 
stadd polyp, hvilken intagit den förres plats som basalpolyp 
1 midtellinien af rachis, och 1 sin ordning våxer fatt sina 
båda föregångare och drager sig åt andra (högra) sidan 
om terminalpolypen*. Af det foreliggende Material ud- 
bryder de laterale Polyper efter Endepolypens Dannelse 
uden nogen saadan Vandring, som Lindahl antyder, og 
efterat et Par laterale Polyper ere fremkomne paa hver 
Side, udvoxer Rachis i Bredden, hvorpaa de central-dorsale 
og senere de dorsal-laterale Polyper udvikle sig efterhaan- 
den, ligesom de laterale Polyper tiltage i Antal. Udvikligen 
af Rachis og det Rum, som derved vindes, synes at være 
det Bestemmende for Polypernes Anordning; men forøvrigt 
kan intet sikkert herom siges, førend man har en langt 
større og mere sammensluttende Række af Exemplarer, 
end vi have havt. 
Vi skulle gaa til at fremstille den indre 
Bygning af Umbellula encrinus. 
nu over 
Den anatomisk-histologiske Bygning. 
De 4 store Længdekanaler, der gjennemløbe hele 
Stokken, undergaa Forandringer væsentligt, eftersom Axe- 
dreiningerne foregaa. Paa Midten af Stokken ere Kanalerne 
næsten lige vide; Ventral- og Dorsalkanalen er dog lidt 
større i Omfang end Sidekanalerne, og her ligger Axen i 
Centrum. - Længere op imod den skedeformige Udvidning, 
hvor Axen nærmer sig Ventralfladen, begynder samtlige 
Lengdekanaler at fordreie sig noget, hvilken Fordreining 
bliver endnu stærkere i den skedeformige Udvidning og i 
selve Rachis. Vi maa henvise til de to Tversnit, Tab. 
VIII, Fig. 30 og 31, for at gjøre det ret forstaaeligt. Det 
første Tversnit, Fig. 30, er foretaget omtrent midt paa den 
skedeformige Udvidning, og her viser det sig, at Axen er 
skudt helt hen til Ventralsiden, Fig. 30, a; Ventralkanalen 
er ligesom dreiet og udvidet mod Sidekanalen, Fig. 30, b. 
Den høire Sidekanal er trukken mod Dorsalkanalen og temmelig 
udvidet imod Coenenchymvæggen, Fig. 30,c. Dorsalkanalen 
Den norske Nordhavsexpedition. Danielssen og Koren. Pennatulida. 
41 
Dr. Lindahl has given an outline representation of 
the development of the polyps, as he has supposed it to 
proceed. This is only a hypothesis, however, because it is 
based on no 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 he has sup- 
posed. We quite agree with him 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 im 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 on each side, the rachis expands in breadth, 
and then the centro-dorsal, and, subsequently, the dorso- 
lateral polyps, develope themselves, gradually, whilst, also, 
the lateral polyps become more numerous. The develop- 
ment 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 be 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 
of Umbellula encrinus. 
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 dila- 
tion, 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. 30a). The ventral canal appears, as if twisted, and dilated 
6 
