98 



"Unger, efterat de have tbrladt Moderen,' kan jeg ingen 

 Besked give; thi jeg har ikke kunnet følge dem saa langt. 

 Men Kowalevsky og Marion have iagttaget, at Unger ne hos 

 de Arter, de have observeret, altid satte sig fast ved den 

 brede Ende, som de forresten vare tilbøielige til at antage 

 for Ungens Hovedpart! (region céphalique), naar de toge 

 Hensyn til. den Maade, paa hvilken den bevægede sig, 

 nemlig altid med den brede Del foran. De angive ikke, 

 at der i den brede Ende var en Mundaabning, men tvert- 

 imod, at Mundaabningen dannede sig i den smale Del, først 

 efter atUngerne havde fæstet sig. Dersom de af mig iagt- 

 tagne Unger skulde læste sig ved den brede Ende, maatte 

 Larvemunden forsvinde og en ny Mund dannes, en For- 

 vandling, der jo ikke er fremmed for de lavere Dyr, men 

 endog temmelig almindelig hos de fra Coelenteraterne 

 ikke saa fjernt staaende Echinodermer. De nysnævnte 

 Forskeres Udtalelser med Hensyn til Befæstningsmaade 

 staar forresten i Strid med Kowalevsky's tidligere gjorte 

 Iagttagelser over Udviklingen af Sympodium coralloides; 

 thi i hans Afhandling: „Zur Entwickelungsgeschichte der 

 Alcyoniden" x udti-ykker han sig saaledes: „Wåhrend der 

 Verwandlung heftet sich die Larve bekanntlieh mit ihrem 

 vorderen zugespitzten Ende an und zieht den hinteren 

 mehr ansgebreiteten Pol ein, wobei aus demselben der 

 Magen entsteht." — Jeg er dog tilbøielig til at antage, at 

 mine Larver fæster sig ved den smale Ende, at Larve- 

 mimden bliver permanent, og at, idet den tidligere omtalte 

 Indkrængning afEctodermet forlænger sig og danner Svæl- 

 get, fæste Skillevæggene (Mesenterierne) sig paa dette. Jeg 

 paaviste, at i et temmelig fremrykket Larvestadium udgik 

 der fra Mavehulheden en Mængde listeformige Forlængelser: 

 de begyndende Mesenterier. Enten smelter flere af disse 

 sammen, eller flere af dem forsvinde (absorberes), saa at 

 Antallet bliver det regulære, nemlig 8. Det er jo netop i 

 Larvens brede Ende, at disse Skillevægge optræde, og det 

 tør ogsaa af den Grund være antageligt, at Ungen fæster 

 sig ved den smale Ende og altsaa ikke undergaar den 

 Metamorphose, som vilde være Tilfældet, om Befæstelsen 

 skede ved den tykke Del (Hoveddelen). 



Det er ganske mærkeligt, at Spikeldannelsen hos 

 disse Arter optræder saa overordentlig tidligt, længe før 

 Larven har forladt Ægget, hvilket ikke tidligere har været 

 observeret; thi ifølge Kowalevskys og Marions Iagttagelser 

 indtræder Spikeldannelsen, først efter at den fritsvømmende 

 Unge har sat sig fast. Men den Omstændighed, at Spik- 

 lerne optræde saa tidligt hos den i Ægget indesluttede 

 Larve, kort Tid efter Ectodermet er dannet, og førend 

 nogen Antydning til Bindevæv kunde iagttages er, saa 

 forekommer det mig, et stærkt Bevis for, at Spiklerne ere 

 Produkter af Ectodermcellerne og ikke af Bindevævet. 



1 Zoologischer Anzeiger. 2 Jahrg. pag. 491. 



young ones, after they have abandoned the parent animal, 

 is a subject upon which I can give no information, as I 

 have been unable to follow them so far. But Kowalevsky 

 and Marion have remarked, that the young of the species 

 which they have observed always became adherent by 

 the broad extremity, which, however, they were disposed 

 to assume to be the cephalic part of the young one (region 

 céphalique), when they regarded the manner in which it 

 moved itself, that is, always with the broad extremity in 

 advance. They do not state that there was an oral aperture 

 in the broad extremity but, on the contrary, that the oral 

 aperture was formed in the narrow part, and not till after the 

 young ones had secured themselves fast. If the young 

 ones, observed by me, were to secure themselves fast by 

 the broad extremity, the larva mouth would necessarily dis- 

 appear and a new mouth be formed, a change which, indeed, 

 is not unknown in the lower animals, but is, even, rather 

 common in the Echinodermata, not so very distantly related 

 to the Coenteralata. The report of the Naturalists just 

 named, with reference to the mode of attachment stands, 

 however, in opposition to the observations previously made 

 by Kowalevsky, on the development of Sympodium coral- 

 loides, because in his Memoir ,.Zur Entwickelungsgeschichte 

 der Alcyoniden" 1 he thus expresses himself. „Wahrend der 

 „ Verwandlung heftet sich die Larve bekanntlieh mit ihrem'' 

 „ vorderen zugespitzten Ende an unci zieht den hinteren" 

 „mehr ausgebreiteten Pol ein, wobei aus demselben der" 

 „Magen enststeht." I am, however, disposed to assume that 

 my larvæ fasten themselves by the narrow extremity, and 

 that the larva mouth is permanent; further, that whilst the 

 depression in the ectoderm, previously spoken of, becomes 

 prolonged and forms the gullet, the divisional walls (Mesen- 

 teries) secure themselves to it. I showed that, in a tol- 

 erably advanced larva-stage, there proceeded from the ven- 

 tral cavity a number of fillet-formed prolongations — the 

 rudimentary mesenteries. Either, several of these pass 

 into each other, or several of them disappear (are absorbed) 

 so that the number becomes the usual one, that is 8. It 

 is just in the broad extremity of the larva that these 

 divisional walls appear, and it may, for that reason, be 

 presumed that the young one fastens itself by the narrow 

 extremity and, therefore, does not undergo such a meta- 

 morphosis as would be the case if the attachment was 

 made by the thick part (the cephalic part). 



It is quite remarkable that the spicular formation in 

 these species appears so extremely early, long before the 

 larva has abandoned the ovum, a fact which has not been 

 previously observed; according to Kowalevsky and Marions 

 observations, the spicular formation does not appear, till 

 after the freely-swimming young one has secured itself fast., 

 But the circumstance that the spicules appear so early in 

 the larva enclosed in the ovum, a short time after the form- 

 ation of the ectoderm, and previous to any indication of 

 connective-tissue being observed is, it appears to me, a 

 strong proof that the spicules are products of the ectoderm 

 cells, and not of the connective-tissue. 



1 Zoologischer Anzeiger. 2 Jahrg., pag. 491. 



