21 



nalen lige til Armenes j r derste Ende, Tab. II, Fig. 4 a. 

 Paa denne Strækning indtager selve Nervegrenen omtrent 

 den samme Tykkelse; men den er forsynet med en Mængde 

 Ganglier, som væsentlig ligge paa dens ventrale Side, Tab. 

 IV. Fig. 4 b. Foruden mange Smaagrene afgives til hver 

 Pinnul en Hovedgren, der følger dennes Dorsalflade, og paa 

 hvis ventrale Side ligger lignende Ganglier som i Armen. 

 Disse Ganglier ere elliptiske, indtage omtrent Midten af 

 ethvert Tied og udsende Grene til Epithel og Muskler, af 

 hvilke dog der er 4, som ere meget fremtrædende, og som 

 Professor Carpenter allerede forlængst har gjort opmærksom 

 paa. Tab. III, Fig. I 1 a, b. Men foruden disse 4, der 

 udspringe fra Dorsal- og Ventralsiden, ndgaa der ogsaa til 

 hver Side niindst 2, næsten ligesaa tykke som de nævnte 

 4, Tab. III, Fig. lic, c. Alle disse (-irene, der tåge 

 deres Udspring fra Ganglionperiferien, lø,be udelte et kort 

 Stykke Vei, men dele sig saa dichotomisk for senere at 

 forsyne Epithel og Muskler med Nervetibriller, Tab. III, 

 Fig. 1 1 d. Et Længdesnit af Nerven med det aflange 

 Ganglion har et Udseende, som om Gangliet laa aldeles 

 udenpaa Nerven, Tab. V, Fig. 7, hvilket dog ikke er Til- 

 fældet. Nervestammen er sammensat af en Mængde fine 

 Fibriller, der ligge ved Siden af hverandre uden nogen 

 Forbindelse mellem dem, Tab. V, Fig. 7 a; men dels ind 

 imellem Fibrillerne, dels udenpaa dem, sees større og mindre 

 aflange, tildels bipolare Ganglieceller med sine store, mørk- 

 farvede Kjerner. Gangliet bestaar af mange store Ganglie- 

 celler. der ligge paa Nervestammen, hvorfra det faar flere 

 Fibriller, som blande sig ind imellem Cellerne, Tab. V, 

 Fig. 7 b. Paa et Tversnit af en lignende Nerve med Gang- 

 lion sees Nervefibrillerne som stærkt farvede Punkter, der 

 synes at omgive de store, dels bi- dels multipolære Celler 

 med deres næsten centralbeliggende, lidt aflange Kjerne, 

 Tab. Ill, Fig. 11. Samtlige Nervestammer og deres For- 

 greninger danne faste, cylinderformede Traade uden at 

 indeslutte noget Kar eller have noget hult Ruin, saaledes 

 som enkelte Forskere har angivet. 



Centralorganet for det ventrale Nervesystem ligger 

 mesodermalt omkring Svælget, hvor det danner en femkantet 

 Ring, og er først paavist af Dr. Jickeli, Tab. IV, Fig. 10. 

 Imedens enkelte Forskere har benægtet Rigtigheden af 

 Jickeli's Iagttagelser, ere disse dog senere konstaterede 

 saavel af Hamann som Perrier. Hos Bathyerinus Carpen- 

 teri ligger den nævnte centrale Ring strax under Mund- 

 aabningen, omgiver Svælget og er indesluttet af Bindevævet, 

 ligesom den tildels dækker Vandkarringen, Tab. IV, Fig. 

 10 a. Den er temmelig tyk og afgiver en Mængde Grene. 

 hvoraf 10 ere tykkere end de øvrige og følge de 5 Vand- 

 kargrene, en paa hver Side. Idet disse Nervegrene ere 

 naaede hen mod Midten af 3die Radiale, dele de sig atter 

 i 2, saaledes at hver at disse gaa ind i Armens ventrale 

 Væg ved Siden af Vandkarret, Tab. II, Fig. 4 c. Hver 

 Arm har altsaa 2 ventrale og 1 dorsal Nervegren. Armens 

 ventrale Nervegrene give til hver Pinnul 2 Grene, der 



across the dorsal canal, quite to the outermost extremity 

 of the arm (Pl. II, fig. 4 a). Upon this stretch the aerve- 

 branch itself retains about the same thiekness, but is fur- 

 nished with a multitude of ganglia, situated ohiefly on its 

 ventral side (Pl. IV, fig. 4b). Besides many small branches, 

 a chief branch is given off to each pinnule, which follows 

 the dorsal surface of the latter, and on whose ventral side 

 similar ganglia to those of the arm are situated. These 

 ganglia are elliptical, occupy nearly the middle of each 

 joint and send out branches to the epithelium and muscles; 

 of which, however, there are 4 that are very prominent 

 and which Professor Carpenter has already, long ago, 

 called attention to (Pl. III, fig. Ila, b). But besides 

 these 4, which spring from the dorsal and ventral side, 

 there also issue, to each side, at least 2 ganglia, almost as 

 thick as the 4 named (Pl. III, fig. Ile, c). All these 

 branches. which have their origin in the periphery of the 

 ganglion, ran a short distance without division. but they 

 then divide themselves dichocotomically, so as to subse- 

 quently supply the epithelium and muscles with nerve-fibrils 

 (Pl. III, fig. Ild). A longitudinal section of the nerve with 

 the oblong ganglion has the appearance, as if the ganglion 

 lay entirely on the outside of the nerve (Pl. V, fig. 7), 

 which is, however, not the case. The nervous stem is 

 composed of a multitude of delicate fibrils which lie along- 

 side each other, without any connection taking place between 

 them (Pl. V, fig. 7 a), but partly in between the fibrils 

 partly outside them, larger or smaller oblong, partly bi- 

 polar ganglial cells with their large dark-coloured nuclei are 

 observed. The ganglion consists of many large ganglial cells 

 which lie upon the nervous stem, whence it receives many 

 fibrils which mix themselves in between the cells (Pl. V, 

 fig. 7 b). In a transverse section of such a nerve with 

 ganglion, the nerve-fibrils are seen like dark-coloured 

 points, which seem to indicate the large, partly bipolar 

 partly multipolar cells with their nearly centrally situated, 

 slightly oblong nuclei (Pl. III, fig. 11). All the nerve-stems 

 and their ramifications form firm cylindriform threads, 

 without enclosing any vessel, nor have they any hollow 

 space, as has been stated by some investigators. 



The central organ of the ventral nervous system lies 

 mesodermally round the cesophagus, where it forms a five- 

 sided ring, and has been first shown by Dr. Jickeli (Pl. 

 IV, fig. 10). Although a few investigators have denied 

 the correctness of Jickeli's observations these have subse- 

 quently been confirmed by Hamann as well as Perrier. In 

 Bathyerinus Carpenteri. the central ring spoken of lies im- 

 mediately below the oral aperture, surrounds the æsophagus 

 and is enclosed by the connective-tissue, wliile it also partly 

 covers the water-vessel ring (Pl. IV, fig. 10a). It is pretty 

 thick, and gives off a multitude ol branches. of which 10 

 are thicker than the rest and follow the 5 water-vessel 

 branches, one on each side. When these nervous branches 

 have reached as far as to near the middle of the 3rd 

 radial, they again divide themselves into 2, in such a man- 

 ner that each of these passes into the ventral wall of the 

 arm at the side of the water-vessel (Pl. II. flg. 4 c). Each 



