51 



Buggangliekjæden (se Fig. 1) er ikke vanskelig 

 at observere saavel hos levende Exemplarer som 

 hos Specimina opbevarede i fortyndet Spiritus. Man 

 hehover blot med Forsigtighed at n(ll)rede Branehial- 

 fodderne til hver Side og iiidstille Mikroskopet skarpt 

 ]iaa Bngfladen af Dj-ret, og denne Del af Xerve- 

 s\-stemet vil, ialfald delvis, klart og tydeligt sees, 

 Ilden at nogen virkelig Dissection er ibrnoden. Dog 

 er dens forreste Del altid temmelig vanskelig at -ob- 

 servere, da den fordetmeste skjules af de lidet gjen- 

 ni-msigtige Kindbakker og af Kjæverne. Buggang- 

 liekjæden viser en meget udpræget stigedannet Form, 

 idet den be.staar af "2 vidt adskilte stærke Xerve- 

 stammer, som i hvert Segment forltindes med en 

 dobbelt Tværcommissur. Paa dette Sted viser hver 

 Xervestamme en temmelig svag ganglios (Jpsvulm- 

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

 udspringer. Det ene Par af disse Xerver trænger 

 ind i de respective Branchialfodder, medens det 

 andet Par synes at innervere de Muskler, der fra 

 Kroppen passerer til Basis af disse Lemmer. En 

 anden betydelig svagere Xerve udspringer omtrent 

 fra Midten af enhver af Længdecommissurerne og 

 synes at ende i Legemets Sidemuskler. Antallet af 

 de Xerveknuder, der sammen med ("ommissurerne 

 danner Buggangliekjæden, er paa hver Side lo (se 

 Fig. 1). Heraf er de 3 tbrreste Par bestemte for 

 Kindbakkerne og de 2 Par Kjæver, det hageste Par 

 for (jrenitalsegmentet, de 11 øvrige for de 11 Par 

 Branchialfodder. Buggangliekjæden er saaledes ind- 

 skrænket til Forkroppen alene. I Bagkrojjpen fort- 

 sættes rigtignok de 2 Xervestammer lige til Enden 

 af sidste Segment, men uden her at være forbundne 

 \"ed Tværcommissurer og uden at danne tydelige 

 (ianglier. I hvert Halesegment udsender disse Xerve- 

 stammer fine Xervegrene, hvoraf nogle synes at ud- 

 lirede sig i Halens Muskulatur, medens andre ender 

 med en liden ganglios Ojisvulmning lige uniler Huden 

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

 ordentlig tin Borste (Folebor.ste) at springe frem, til- 

 dels omgiven af sniaa Hudpapilbu- (Fig. 9). 



Angaai'nde den ]\raadr, livorjjaa de ovrige Xer- 

 ver endei', skal her blot omtales l-'orhoIdet med de 

 til Iste 1'ai' F(dere gaaendc Xerver og Synsiu'rverne. 



Førstr 1'ai' i''idcri's Xi'r\i'r uds])ringer (se Fig. 4) 

 tilsyneladende fra det basale Parti af Synsnerverne, 

 idet begge Xerver ved sit Uflsjiring er omgivet af 

 en fælles Xerveskede. De træder deretter til hver 

 Side som en tynd Stamme ind i Iste Par Føleres 

 Basis og tVirtsætter sig igjennem deres Axe indtil 

 lienimod Spidsen. Her deler Xerven sig (,se Fig 2) 

 i 2 (irene, der tilsammen daniu^r en betvdeliu: irans:- 



Ort f5 



lios ]\Iasse ved Spidsen af Føleren. Fra denne 



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

 ditHcult to examine, either in living specimens or in 

 tliose preserved in diluted spirit. It is only neces- 

 sary to turn tile liranchial legs carefully to eitlier 

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

 ventral surface, when this part of the nervous sy.<- 

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

 clearly and distinctly, without the necessity of 

 actual dissection. The front part, however, is always 

 rather ditftcult of observation, as it is generally 

 almost hidden by the l)ut slightly transparent man- 

 dibles and by the maxillæ. The ventral ganglion 

 chain exhil)its a marked ladder-like form, in that it 

 consists of 2 strong, widely-se|)arated nerve-stems, 

 whieh are connected in each segment by a double 

 transverse commissure. Here each nerve-stem exhi- 

 bits a rather sligiit ganglionic dilatation (see fig. 5), 

 on the outer side of which, 2 strong nerves have 

 their origin. Oiie of these pairs of nerves jtenetrates 

 into the resj)ective liranchial legs, while the other 

 pair ap])ears to innerve the muscles passing from 

 the body to the base of those ai)pendages. Another 

 much weaker nerve has its origin almost in the 

 middle of each of the longitudinal commissures, and 

 a])pears to end in the lateral muscles of the bød\-. 

 The number of ganglia that, together with the com- 

 missures, form the ventral ganglion chain, is 15 on 

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

 are destined for the mandibles and the two pairs of 

 maxillæ. the hindmost jjair for the ,genital segment, 

 and the reniainin.g 11 for the 11 pairs of branchial 

 legs. The ventral gan,gliøn chain is thus confined to 

 the anterior division of the body. It is true that 

 the 2 nerve-stems are continued im the himler part of 

 the bod_\- as far as the end of the last segment, but 

 without being there connected by any transverse 

 lonnnissures. and without forming distinct ganglia. 

 In ever}- caudal segment these nerve-stems send out 

 delicate rami, some of which ajjpear to spread over 

 the caudal musculature, while others end in a little 

 ganglionic tuberosity just below the integument isee 

 fig. 8.) At these places an exceedingly fine In-istle 

 (sensory bri.stle) is always seen to protrude, parti- 

 ally surrounded by small cutaneous papillæ (fig. i^l). 



With regard to the manner in which the re- 

 maining nerves end, only the circumstances relating 

 to those of the 1st pair of antennæ, and the o])tic 

 nerves will be mentioned here. 



Tlu^ nerves of the 1st pair of antennæ (see fi.g. 4) 

 apparently originate from the basal |iart of tlie 

 optic nerves, both nerves Ijeing surrounded at their 

 origin by a common neural-sheath. They then pass 

 to eitlier side in the form of a thin stem into tlie 

 base of the first ])air of antennæ, wlience they con- 

 tinue along the axis of the latter almost to tlie 

 extremit\-. Here the nerve divides ,see fig. 2) into 

 2 branches, wliieli toicether form a considerable 



