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7
Do 4 store Længdekanaler have som sædvanligt sine
4 Septa, der fæste sig paa Axeskeden, hvormed de smelte
sammen, Fig. 13, a. I den bulbøse Del forgrene
Septa-erne sig, idet de gaa over i Sarcosomaet, hvor de bidrage
til Dannelsen af store Tverkanaler, Fig. 13, b. I den
øvrige Del af Stilken samt i Hachis foregaar ingen saadan
Deling af Septa. Disse bestaa af en tynd, hyalin
Binde-vævsmembran, hvori findes en Mængde fine
Ernæringska-naler, og paa hvis begge Flader er en
Epithelialbeklæd-ning, dannet af lignende Celler som de, der beklæder den
hele Kanal, og som ovenfor ere omtalte. I Stokkens øverste
Del ere Sidekanalerne ganske sammenskrumpede; den
ventrale Knnal er noget videre end Dorsalkanalen.
Generationsorganerne udvikle sig i Sidekanalerne. I
Beskrivelsen af den ydre Fonn omtalte vi, at hvor de
uudviklede Polyper ophøre paa Stilkens bulbøse Del,
findes der paa liver Side en Række Zooider. Disse have en
temmelig vid Mundaabning, Fig. 14, e, et cylindrisk Svælg,
hvis nederste, frie Ende har en rund, tyk Rand, der rager
ind i Sidekanalen, Fig. 13, d. 14, f. Fra hver af denne
tykke Svælgrands Sider udgaar et temmelig bredt
Septulum, der fæster sig paa Sidekanalens Væg, Fig. 13, e,
og hvortil et Gastralfilament er bundet, Fig. 13, /, hvis
yderste Ende svømmer frit i Kanalens Fluidum. I det
brede Septulum opstaa Kjønsorganerne og dannes af
stilkede Kapsler, Fig. 14, g, hvori Kjønsproduktet udvikler
sig. De Exemplarer, vi undersøgte, vare Hunner, — der
var Æg i alle Udviklingsstadier og i saa rigelig Mængde,
at de hængte *paa Septula som Drueklaser og opfyldte
næsten fuldstændigt Sidekanalerne, Fig. 14. Desforuden saaes
ogsaa enkelte Embryoner, der havde forladt Ægget og laa
frit i Kanalen. Hvor denne Rigdom af Æg fandtes, var
saavel Ventral- som Dorsalkanalen meget sammentrykket,
Fig. 14, vk, dk\ men i samtlige Kanaler kunde dog
Fluidumet cirkulere. Udvendig paa den bulbøse Del af
Stilken viste den stærke Udvikling ef Grenerationsorganerne
sig derved, at Overfladen var ujævnt udvidet og opsvulmet.
Fig. 12, der er aabnet efter Ventralfladen, illustrerer
hvorledes Kjonsorganerne udvikle sig i Sidekanalerne.
Ven-tralkanalen og Axen a ere borttagne i den Strækning af
Stilken, hvor Zooiclerne indtage de før beskrevne
Siderækker, — og hvorved Dorsalkanalen, Fig. 12, b, bliver
synbar. I de udvidede Sidekanaler sees de clrueformigt
udviklede Kjønsorganer, Fig. 12, c. De fuldt udviklede
Polyper ere golcle, medens i de to sidste Rækker af
uudviklede Polyper kun findes enkelte Generationskapsler, der
ligeledes rage ind i Sidekanalerne for der at udvikle sit
Ivjonsprodukt.
Vi have Grund til at antage, at Svavaslægten føder
levende Unger, og saavidt vi have kunnet erfare, fødes Un-
The 4 large longitudinal canals have, as usual, their
4 septa; which are attached to the sheath of the axis,
and with which they become fused together (fig. 13, a). In
the bulbous part, the septa branch off as they pass over
into the sarcosoma, and contribute to the formation of
large transversal canals (lig. 13, b). In the remainder of
the stem, and also in the rachis, no such dividing of the
septa takes place. The septa consist, of a thin, hyaloid,
connective-tissue membrane; in which is found a multitude
of minute nutrient canals, and on both of whose surfaces,
there is an epithelium covering, formed of similar cells,
to those which cover the entire canal; and which have
already been spoken of. In the superior part of the stalk,
the lateral canals are quite shrunk together. The ventral
canal is somewhat wider than the dorsal canal.
The generative organs develope themselves in the
lateral canals. In the description of the exterior habit;
we stated, that at the point on the bulbous part of the
stem where the undeveloped polyps cease, there is found
upon each side, a series of zooids. These have a rather
wide oral aperture, (fig. 14, e) and a cylindrical gullet,
whose lower free extremity has, a round, thick margin,
which projects into the lateral canal (fig. 13, d. 14, /’).
From each of the sides of this thick gullet-margin ; a
pretty broad septulum proceeds, which attaches itself to
the wall of the lateral canal, (fig. 13, e), and to which a
gastral filament is secured, (fig. 13,/) whose outer
extremity floats free, in the secretion of the canal. The
sexual organs originate in the broad septulum, and are
formed of pedunculated capsules, (fig. 14, g), in which the
sexual product developes itself. The specimens which we
examined were females; there were ova in all stages of
development, and in such abundant quantities, that they
depended from the septula, like clusters of grapes, and
almost, completely, filled up the lateral canals (fig. 14).
Besides these, a few embryos which had forsaken the
ovum, and lay free in the canal, were also observed.
Where this wealth of ova was found, both the ventral and
dorsal canal were much shrunk together, (fig. 14, v, k, d, k)
but in all the canals, however, the secretion could
circulate. Outside, on the bulbous part of the stem; the great
development of the generative organs became apparent
from this; that the surface was unevenly dilated and
swollen. Fig. 12, in which the dissection is made from the
ventral surface; illustrates the manner in which the
sexual organs develope themselves in the lateral canals. The
ventral canal and axis (a) are removed in that portion of
the stem where the zooids assume the lateral series
previously described; and the dorsal canal (fig. 12, b) becomes
thus, visible. In the dilated lateral canals, the grape
formed developed sexual organs . are observed (fig. 12, c).
The fully developed polyps are sterile, whilst, in the two
last series of undeveloped polyps, only a few generative
capsules are found; these also, project into the lateral
canals, in order to develope there, their sexual product.
We have reason to believe, that the genus Svava,
gives birth to living young, and as far as we have been
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