35 



moddele hovetltrækkeiie af kiiDpskyilniiigeiis forloli. i^fter 

 frk. Bonnevies meddelelse. 



Den første antydning til stoloms videre udvikiing 

 viser .sig s;erdeles tidlig. ..Iiv(ir kno|)i)en cndnu kun sees 

 som en liden udbugtning paa moderdyret". Peril)rancliial- 

 srekkene anlægges nemlig da ud fra stoloens indri' ])iære 

 paa den niaade, at dennes epithelvægge viser to laterale 

 fortykkelser, der siden vokser ud som to laterale epithel- 

 plader uden lumen. 



Naar da siden den unge knop er anlaiit linder man, 

 som tidligere bekjendt, og som ovenfor metldelt efter Hei- 

 (}i-rs beskrivelse, disse anlæg paa hoir(> og venstre side af 

 entodermrøret; kun forbliver de lamgere tid i forbindelse 

 med dette. .,Nerveroret-' (dorsalroret vilde her ikke være 

 en helt ud træffende betegnelse) anlægges endnu. for peri- 

 branchialsækkens forbindelse med entodermroi'et er afbrudt 

 ud fra begge de to periliraneliialsækanlæg, idet disse for- 

 bindes med hinanden ved et ror, der bagtil vokser rundt 

 tarmen (se fig. 2, pl. X); og samtidig dermed eller umid- 

 delbart derefter dannes anlægget til 2 epitiieltappe, der i 

 form af solide strenge vokser forover og forener sig rundt 

 tarmen. Inde i den store cellemasse ved dette forenings- 

 pnnkt dannes nu et hulrum (himen) endnu, for noget saa- 

 dant forekommer i eijithelstrengene. Man tinder den saa- 

 ledes skildrede proces illustreret af figurerne 2 og 3, pl. 

 X. Under den videre udvikiing losner nervesystemet sig 

 efterhaanden fra sanimenhængen med peribranchialsækken 

 (fig. 4 og 5. pl. X). 



Udviklingens videre forlob foregaar nu som almindelig 

 bekjendt fra tidligere arbeider. Gangliet afsnores fra 



nerverørets dorsale side (Seelhjer' 



anlæg til peribran- 



chialsækken forener sig til dannelsen af cloaken. Nerve- 

 systemets 2 rør, der omgiver tarmen trrekkes ud til fine 

 traade. (Se forøvrig foranstaaende afhandling og KorscheU 

 og Heiders lærebog). 



DJdemnidæ og Diplosomidæ. 



Denne grui^pe er blevet studeret af (rvcjenhuur. Oa- 

 nin. Giard, Della Tcdle (13), Salensky (55) og Caidleri/ 

 (9, pag. 101 ffg. Kap. Sur la morphologie des bourgeons 

 des Didemnidæ). 



Jeg folger her Caidlerijt^ indgaaende undersøgelser og 

 henviser angaaende den addre litteratur til lians arl^eide. 



I overensstemuudse med tidligere undersogelser kon- 

 staterede Cmdhn-y. at hver knop hos D/plosoiiia gdafinosuni 

 fremgaar af 2 knopanlæg, nemlig en „Iiourgeon thoracique- 

 og en ..bourgeon abdominal-'. 



Medens man tidligere mente, at ..Ijourgeon thoracique-' 

 frenigik som en udbugtning af tarmtractus, fandt Ccdlery, 

 at der hos DipJosoDia tindes et distinkt udviklet epicardiwn, 

 og at knopanlægget dannes, idet en udbugtning af dettes 



features in tiie courst; of Iniddiiig. according to Miss Bon- 

 nevie'.'' account. 



The first indicatioii of tlie furtlier tlevelopment of the 

 stoloii, appears very early. ..wlieii tlie bud only ajijiears 

 like a slight s\v(dling on the mother animal". The peri- 

 branchial cavities thcii begin to form from the inner vesicle 

 of the stolou, the epithelial walls of tliat vesicle showing 

 two lateral tliickeniiigs, wliieh subsequently grow out as 

 two lateral, epithelial lamellæ, without a himen. 



When, later on, the young bud comniences to form. 

 these rudiments are fonnd, as already known, aud as stated 

 above from Heiders descriptioii. on the right and left sides 

 of the endodermal tube; (uily tliey remain for a longer 

 time in conuection witli it. The ,. nerve-tulie'' (dorsal tube 

 would not be an altogether approiiriate term here (Origi- 

 nates, even beforo the connection of the peribranchial eavity 

 witli the endodermal tube is broken off, from the 2 rudi- 

 ments of the peribranchial eavity, these being connected 

 with one another by a tube which at the back grows round 

 the intestine (see Pl. X, fig. 2); and simultaneously, or 

 imniediately after, the rudiments of 2 epithelial processcs 

 are formed, which grow forward in the form of solid cords, 

 and unite round the intestine. Withiu the large mass of 

 cells at this jioint of union, a eavity (lumen) is now formed, 

 hefore anything of the kind occurs in the epithelial cords. 

 The process here described will be fouud illustrated on 

 Pl. X, figs. 2 and 3. During the further development, 

 the nervous system detaches itself by degrees from its con- 

 nection with the peribranchial eavity (Pl. X. figs. 4 

 and 5). 



The further development now proceeds in the manner 

 generally known from earlier works. The ganglion is con- 

 stricted from the dorsal side of the nerve-tulie (Seeliyer). 

 and the 2 rudiments of the peribranchial eavity unite to 

 form the cloaca. The 2 tubes of the nervous system, which 

 encircle the intestine, are drawn out into fine filainents. 

 (See also the preceding paper, and KorscheU and Heiders 

 text-book). 



Didemnidæ and Diplosomidæ. 



This group has beeii stutlied by Geyenhnur, Ganin, 

 Giard, DelJd Valle (13), Salensky (55) and CanUery (9, 

 p. 101, etc; Chap. Sur la morphologie des bourgeons des 

 Didemnidæ). 



I will here follow Caidlery^s minute investigations, 

 and direct attention to iiis work for information regarding 

 the earlier literatnre. 



ln accordauce with earlier investigations, CaaJlery 

 demonstrated that every bud in Diplosoma gélatinosum 

 proceeds from 2 bud-rudiments. iiamely, a ..bourgeon thora- 

 cique-' and a „bourgeon abdominal-'. 



Whereas it was once thought that the ..bourgeon 

 thoracique-' appeared as an evagination of the intestine, 

 Caidlery fonnd that in Diplosoma tiiere is a distinctly de- 

 veloped epicardiam, and that the bud-rudiment is formed 



