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os, at Brandts Conjectur er rimelig, nemlig at Æggene 

 og Zoospermerne, efterat være komne ud af Kropshulhe- 

 den, og svømme frit i Søen, kunne tilfældigvis trænge 

 ind igjennem de omtalte Organers Aabning, der findes 

 paa Bugfladen, ligesaa godt som man finder fin Sand 

 trængt ind i dem paa den Vei. At antage dem for Ge- 

 nerationsorganer kunne vi ikke; thi foruden at deres 

 Bygning taler derimod, have vi ingensinde seet hverken 

 modne eller umodne Æg eller Spermatozoer i dem, og 

 det uagtet vi jævnlig have truffet paa Æg i Kropshulheden. 

 Vi skulle senere omtale Kjønsorganerne og da paavise 

 deres Sæde. Vi have hos enkelte, næsten vandklare Si- 

 punculider kunnet iagttage, hvorledes disse blæreformige 

 Organer have været fyldte med en saagodtsom farvefri 

 Vædske, hvorledes de under Contractionerne have ud- 

 tømt denne, idet Lumenet i høi Grad er formindsket, og 

 hvorledes efter nogen Tid Blærerne atter ere blevne ud- 

 spændte. Dette i Forbindelse med deres Bygning og 

 deres Udførselsaabning, der er forsynet med en liden 

 Sphincter, giver os Grund til at antage dem for Afson- 

 dringsorganer, — og som saadanne maa vi nærmest hen- 

 føre dem til et Slags Urnyrer. Brandt med Flere ere 

 ogsaa komne til en lignende Antagelse, nemlig at de ere 

 Excretionsorganer. 



GENERATIONSORGANERNE. 



Hos vore to Sipunculus-Arter have vi ikke stødt paa 

 noget Organ, der kunde lede os til at tro, at deri udvik- 

 lede sig Æg eller Spermatozoer; heller ikke have vi hos 

 dem fundet Kjønspr o ducter frit i Kropshulheden eller 

 paa noget andet Sted i Legemet. Vore Undersøgelser 

 ere jævnligen anstillede Midtsommer, og det tør hænde, 

 at just paa den Tid ere Generationsorganerne ikke ud- 

 viklede hos vore bekjendte Sipuncler. Anderledes for- 

 holder det sig med de Phascolosomaer, vi have under- 

 søgt; hos de fleste af dem have vi ikke alene fundet Æg 

 svømmende frit i Kropshulheden; men vi have ogsaa fun- 

 det det Organ, hvori de udvikles. Hos Phascolosoma 

 squamatum, abyssorum, Lovénii, margaritaceum, eremita, 

 vulgare, dannes Æggestokken af to bladformige Membra- 

 ner i Form af Blindsække, der paa den indvendige Flade 

 ere beklædte med et Kjerne-Epithel. Den tager sit Ud- 

 spring fra den Del af Peritoneum, der beklæder den 

 nederste Del af Spiserøret, et lidet Stykke ovenfor Tarm- 

 spiralens Begyndelse, Naar Æggestokken er fuldt udvik- 

 let, omgiver den Spiserørets nederste Del, samt Tarm- 

 spiralens øverste, medens dennes nederste Del ikke fuld- 

 kommen indkapsles, idet nemlig Æggestokken her har en 

 Spalte, hvorved Tarmspiralen bliver synbar. Æggestok- 

 ken er i sin Bygning temmelig simpel; den omtalte 

 Membran danner en hel Del Indkrængninger, dels som 



gans, which we never have seen, and forasmuch as ova 

 and zoospermata are not formed there, the question has 

 been how they could have come in, where no opening 

 exists through which they could pass. We can give no 

 satisfactory answer to this; but it appears to us, that 

 Brandt's conjecture is reasonable, namely that the ova 

 and zoospermata, after having issued out of the peri- 

 visceral cavity, and after swimming freely in the sea, may 

 be able to penetrate into these organs accidentally through 

 the aperture which exists in the ventral surface, just as 

 well as fine sand is found introduced into them in that 

 way. To regard them as organs of generation is impos- 

 sible for us; for besides their structure opposing this 

 notion, 'we have never seen mature or immature ova or 

 spermatozoa in them; and that notwithstanding we have 

 constantly met with ova in the perivisceral cavity. We 

 shall subsequently notice the sexual organs, and then in- 

 dicate their situation. We have been able in some nearly 

 pellucid Sipunculides, to observe how these vesicular or- 

 gans have been filled with a nearly colorless fluid; how 

 they have expelled it during the contractions, while the 

 lumen has been diminished in a great degree, and how 

 after some time the bladders have been again inflated. 

 This, in connexion with their structure and their excre- 

 tory orifice, which is provided with a small sphincter, 

 gives us cause to presume that they are organs of secre- 

 tion, — and as such we must rather consider them to be 

 a sort of primitive kidneys. Brandt and several others 

 have also come to a similar conclusion, namely that they 

 are organs of excretion. 



THE ORGANS OF GENERATION. 



In our two species of Sipunculus, we have not met 

 with any organ which could lead us to believe that ova 

 or spermatozoa were there developed; neither have we 

 in these species found sexual products free in the peri- 

 visceral cavity nor in any other part of the body. Our 

 investigations were constantly made in the middle of the 

 summer; and it may be that just at that season the or- 

 gans of generation are not developed in our known Si- 

 punculi. But the case is quite different with the Phas- 

 colosomas we have examined. In most of these we have 

 not only found ova floating freely in the perivisceral ca- 

 vity; but we have also found the organ where they are 

 developed. In the Phascolosoma squamatum, abyssorum, 

 Lovénii, margaritaceum, eremita, vulgare, the ovary is 

 formed by two leaf-like membranes in the shape of cæca, 

 of which the interior surface is covered with a nucleal 

 epithelium. It takes its issue from that part of the 

 peritoneum which covers the lower part of the oesopha- 

 gus, a little way above the commencement of the spiral 

 of the intestine. When the ovary is fully developed, it 

 surrounds the lower part of the oesophagus and the up- 

 per part of the spiral of the intestine; while the lower 

 part of the spiral is not completely incapsulated; the 

 ovary having here a fissure through which the spiral of 

 the intestine is visible. The ovary is in its structure? 



