121 



Blærer, dels som smalere Blindsække, hvilke alle ere be- 

 klædte med et Epithel, der er forsynet med. temmelig store 

 Kjerner. Indeni disse Blærer og Blindsække have vi 

 fundet Æg i alle Udviklingsstadier. Efterhaanden som 

 Æggene modnes, udspændes den tynde Membran, bliver 

 alt tyndere og tyndere, indtil den brister, og da sees Æg- 

 gene i store Masser dels mellem Tarmslyngningerne, dels 

 i Kropshulheden. Naar Æggene paa denne Maade ere 

 frigjorte, sees kun enkelte membranøse Fnug at hænge 

 paa Spiserøret og Tarmspiralen som de sidste Rester, 

 der ere tilbage af Æggestokken. Undersøges disse Re- 

 ster under Mikroskopet, vise de sig at bestaa af meget 

 udvidede Blærer eller Blindsække, der ere beklædte med 

 det tidligere omtalte Epithel ; men forøvrigt ere de ganske 

 tomme. Medens Æggene fortsætte sin Udvikling i Krops- 

 hulheden, forsvinde ogsaa de sidste Rester af Æggestok- 

 ken ganske, saa der intet Spor bliver tilbage af den. 

 Saaledes er den almindelige Gang; men da Membranen og 

 dens Blindsække, der danne Æggestokken, ere overor- 

 dentlig fine, hænder det hyppigt, at under Dyrets Sam- 

 mentrækninger og Tarmspiralens Bevægelse løsrive større 

 og mindre Stykker af Æggestokken sig, hvilke kunne 

 indeholde mere og mindre udviklede Æg, der da komme 

 til at flyde om i Kropshulhedens Vædske, hvor de senere 

 udvikles. Nogen Aabning, hvorigjennem Æggene kunne 

 passere udaf Kropshulheden, have vi ikke iagttaget, og vi 

 ere heller ikke tilbøielige til at tro, at der gives nogen 

 saaclan hos de Arter, der af os ere blevne undersøgte. 

 Derimod have vi ofte seet, at paa Kroppens bagerste Ende 

 dannes der snart en Grube, snart en conisk Fremstaaen- 

 hed, alt eftersom denne Del af Dyret sammentrækker eller 

 udvider sig, og medens Gruben under Sammentræknin- 

 gerne er bleven dybere og dybere, er den coniske Frem- 

 staaenhed under Udvidningerne bleven større, meget tyn- 

 dere og næsten gjennemsigtig, uden at vi dog have iagt- 

 taget nogen Ruptur. Imidlertid ere vi tilbøielige til at 

 tro, at naar Æggene ere fuldmodne, brister denne tynde 

 coniske Fremstaaenhed for at lade Æggene blive frie, — 

 en Antagelse, der forresten stemmer overens med enkelte 

 andre Forskeres Mening om Æggenes Frigjørelse. Sam- 

 menholde vi nu disse vore Iagttagelser med de, der af 

 tidligere Forskere ere anstillede med Hensyn til Genera- 

 tionsorganerne, saa mene vi, at de mange Uoverensstem- 

 melser, som virkelig finde Sted, væsentlig grunde sig paa, 

 at neppe Nogen før har seet den virkelige Æggestok, 

 men enten kun løsrevne Stykker af den eller frigjorte 

 Æg, der svømme om i Kropsvædsken. Imidlertid er der 

 en Iagttagelse af Claparéde, anstillet paa to nye Phas- 

 colosomaer ved den skotske Kyst, hvilken synes at tyde 

 hen paa, at han virkelig har seet en Æggestok, dannet 

 paa lignende Maade, som den af os beskrevne. Han siger 

 nemlig 1 ): „Die Eier bilden sich in einem doppelten fla- 

 chen Organ (Fig. 8 o), das zwischen den Darmwindungen 

 unweit vom After liegt. Es wird dasselbe sowohl am 



*) J. Müllers Archiv für Anatom. Physiolog. 1861, pag 541. 

 Taf. 12, Fig. 1 o. 



rather simple: the membrane noticed forms a number of 

 folds, partly as bladders and partly as smaller cæca, 

 which are all covered with an epithelium that has rather 

 large nuclei. Inside of these vesicles and cæca, we 

 have found ova in all stages of development. Gradu- 

 ally as the ova become mature, the thin membrane is 

 stretched, becoming thinner and thinner until it bursts; 

 and then the ova are seen in large masses, partly between 

 the convolutions of the intestine, partly in the perivisce- 

 ral cavity. When the ova are in this manner liberated, 

 only some few membraneous shreds are seen, adhering 

 to the oesophagus and the spiral of the intestine, as the 

 last vestiges remaining of the ovary. When these rem- 

 nants are examined under the microscope, they are found 

 to consist of highly expanded vesicles or cæca, which are 

 covered with the epithelium previously noticed; but they 

 are otherwise quite empty. While the ova continue 

 their development in the perivisceral cavity, the last 

 vestiges of the ovary disappear entirely; so that no 

 trace of it remains. This is the usual course; but as 

 the membrane and its cæca, which form the ovary, are 

 extremely fine, it often happens that, in the contractions 

 of the animal, and in the movement of the spiral of the 

 intestine, larger or smaller pieces of the ovary become 

 detached; and these may contain more or less developed 

 ova, which thus come to float about in the liquid of the 

 perivisceral cavity, wherein they are subsequently deve- 

 loped. We have not observed any opening through which 

 the ova could pass out of the perivisceral cavity, neither 

 are we inclined to think that any such aperture exists in 

 the species which have been examined by us. But we 

 have often seen, that there is formed, on the posterior 

 extremity of the body, sometimes a hollow, sometimes a 

 conical prominence, accordingly as this part of the animal 

 is contracted or expanded; and while the hollow be- 

 comes during the contractions deeper and deeper, the 

 conical prominence becomes during the expansions larger, 

 much thinner and nearly transparent; although we have 

 never observed any rupture. We are however disposed 

 to think that, when the ova are fully mature, this thin 

 conical prominence bursts, in order to let the ova become 

 free, — a notion which moreover agrees with the opinion 

 of some other naturalists as to the liberation of the ova. 

 If we compare these our observations with those made 

 by earlier naturalists in regard to the organs of genera- 

 tion, we think that the many discrepancies which really 

 exist, are owing chiefly to no one having seen the real 

 ovary, but only detached pieces of it, or liberated ova, 

 floating in the perivisceral liquid. However there is one 

 observation of Claparéde, made on two new Phascoloso- 

 mas on the Scotch coast, which seems to indicate that 

 he has really seen an ovary formed in a similar manner 

 to that described by us. He says namely l ): „Die Eier 

 bilden sich in einem doppelten flachen Organ (flg. 8 o) das 



*) J. Müllers Archiv für Anatom. Physiolog. 1861, p, 541, Taf. 12 

 r. 1 o. 



