51 



-Buggangliekjæden (se Fig. 1) er ikke vanskelig 

 at observere saavel hos levende Exemplarer som 

 hos Specimina opbevarede i fortyndet Spiritus. Man 

 behover bbit med Forsigtighed at udbrede Branchial- 

 fodderne til hver Side og ind.stille Mikroskopet skarpt 

 paa Bngtladen af Dyret, og denne Del af Nerve- 

 sjj-stemet vil, ialfald delvis, klart og tydeligt sees, 

 nden at nogen virkelig Dissection er fornøden. Dog 

 er dens forre.ste Del altid temmelig vanskelig at ob- 

 servere, da den fordetmeste skjnles af de lidet gjen- 

 nemsigtige Kindbakker og af Kjæverne. Buggang- 

 liekjæden viser en meget udpræget stigedannet Form, 

 idet den bestaar af 2 vidt adskilte stærke Nerve- 

 stammer, som i hvert Segment forbindes med en 

 dolibelt Tværcommis.snr. Paa dette Sted viser hver 

 Nervestannne en temmelig svag ganglios Opsvulm- 

 ning (se Fig. 5), fra hvis ydre Side 2 .stærke Xerver 

 ndspringer. Det ene Par af disse Nerver trænger 

 ind i de respective Branehialfodder, medens det 

 andet Par synes at innervere de Muskler, der fra 

 Kroppen pas.serer til Basis af disse Lemmer. En 

 anden betj'delig svagere Nerve ndspringer omtrent 

 fra Midten af enhver af Længdeeommissurerne og 

 synes at ende i Legemets Sidemnskler. Antallet af 

 de Nerveknnder, der sammen med Commissurerne 

 danner Buggangliekjæden, er paa hver Side 15 (se 

 Fig. 1). Heraf er de 3 foi'reste Par bestemte for 

 Kindbakkerne og de 2 Par Kjæver, det bågeste Par 

 for Genitalsegmentet. de 11 ovrige for de 11 Par 

 Branehialfodder. Buggangliekjæden er saaledes ind- 

 skrænket til Forkroppen alene. I Bagkro])])en fort- 

 sættes rigtigniik de 2 Nervestammer lige til Enden 

 af sidste Segment, men nden lier at være forbundne 

 ved Tværcomraissurer og uden at danne tydelige 

 (xanglier. I hvert Halesegment udsender disse Nerve- 

 stammer tine Nervegrene, hvoi-af nogle synes at ud- 

 brede sig i Halens Muskulatur, medens andre ender 

 med en liden ganglios Opsvulmning lige under Hixdeu 

 (se Fig. 8). Paa disse Steder sees altid en over- 

 ordentlig fin Borste (Foleborste) at springe frem, til- 

 dels omgiven af snma Hudpapiller (Fig. 9). 



Angaaende den Maade, hvorpaa de ovrige Ner- 

 ver ender, skal her blot omtales Forholdet med de 

 til Iste Par Folere gaaende Nerver og Synsnerverne. 



Første Par Foleres Ner\-er ndspringer ise Fig. 4) 

 tilsyneladende fra det basale Parti af Synsnerverne, 

 idet begge Nerver ved sit Udspring er omgivet af 

 en fælles Nerveskede. De træder deretter til hver 

 Side som en tynd Stamme iii<l i Iste Par Føleres 

 Basis og fortsætter sig igjennem deres Axe indtil 

 henimod Spidsen. Her deler Nerven sig (|se Fig 2) 

 i 2 Grene, der tilsammen danner en betvdelig ffans'- 

 lios Masse ved S])idsen af Føleren. Fra denne 



The ventral ganglion chain (see tig. 1) is not 

 ditScult to examine, either in living specimens or in 

 those preserved in diluted spirit. It is only neces- 

 sary to turn the In'anclual legs carefully to either 

 side, and adjust the microscope close to the animal's 

 ventral surface, when this part of the nervous sys- 

 tem, will, at any rate to some extent, lie seen 

 clearly and distinctly, without the necessity of 

 actual dissection. The front part, however, is always 

 rather difficult of observation, as it is generativ 

 almost hidden by the but slightly transparent man- 

 dibles and by the maxillæ. The ventral ganglion 

 chain exhibits a marked la<lder-like torm, in that it 

 consists of 2 strong, widely-separated nerve-stems, 

 which are connected in ea(di segment by a double 

 transverse commissure. Here each nerve-stem exhi- 

 bits a rather slight ganglionic dilatation (see tig. 5), 

 on the outer side of which, 2 strong nerves have 

 their origin. ( tne of these ])airs of nerves penetrates 

 into the resjiective l)ranchial legs, while the other 

 pair appears to innerve the muscles passing from 

 the body to the base of those appendages. Another 

 much weaker nerve has its origin almost in the 

 middle of each of the longitudinal commissures, and 

 appears to end in the lateral muscles of the bod\'. 

 The number (if ganglia that, together witli the com- 

 missui'es, form the ventral ganglion chain, is 15 on 

 each side (see %. 1). Of these the 3 foremost pairs 

 are destined for the mandibles and the two pairs of 

 maxillæ, the hindmost pair for the genital segment, 

 and the remaining 11 for the 11 jtairs of branchial 

 legs. The ventral ganglion chain is thus confined to 

 the anterior division of the body. It is true that 

 the 2 nerve-stems are continued ini the hinder part of 

 the body as far as the end of the last segment, but 

 without being there connected by any transverse 

 commissures, and without forming distinct ganglia. 

 In every caudal segment these nerve-stems send out 

 delicate rami, some of which appear to spread over 

 the caudal musculature, while others end in a little 

 ganglionic tuberosity just lielow the integument (see 

 fig. 8.) At these places an exceedingly fine bristle 

 (sensory bristle) is always seen to jn-otrude, parti- 

 ally surrounded hy small cutaneous papillæ (fig. 9). 



With regard to the manner in which the re- 

 maining nerves end, only the circumstances relating 

 to those of the 1st pair of antennæ, an<l the optic 

 nerves will be mentioned here. 



Tlie nerves of the 1st pair of antennæ (see fig. 4) 

 ap^jarently originate from the basal part of the 

 optic nerves, 1>oth nerves being surrounded at their 

 origin by a common neural-sheath. They then ])ass 

 to either side in the form of a thin stem into the 

 l)ase of the first jiair of antennæ, whence tliey con- 

 tinue along the axis of the latter almost to the 

 extremity. Here the nerve divides (see fig. 2) into 

 2 brandies, «-hii'li together form a considerable 



