i 
ore 
Buggangliekjaden (se Fig. 1) er ikke vanskelig 
at observere saavel hos levende Exemplarer som 
hos Specimina opbevarede i fortyndet Spiritus. Man 
behover blot med Forsigtighed at udbrede Branchial- 
fodderne til hver Side og indstille Mikroskopet skarpt 
paa Bugfladen af Dyret, og denne Del af Nerve- 
systemet vil, ialfald delvis, klart og tydeligt sees, 
uden at nogen virkelig Dissection er fornoden. Dog 
er dens forreste Del altid temmelig vanskelig at ob- 
servere, da den fordetmeste skjules af de lidet. gijen- 
nemsigtige Kindbakker og af Kjzverne. Buggang- 
liekjeeden viser en meget udpreeget stigedannet Form, 
idet den bestaar af 2 vidt adskilte sterke Nerve- 
stammer, som i hvert Segment forbindes: med en 
dobbelt Tvercommissur. Paa dette Sted viser hver 
‘Nervestamme en temmelig svag ganglios Opsvulm- 
ning (se Fig. 5), fra hvis ydre Side 2 sterke Nerver 
udspringer. Det ene Par af disse Nerver trenger 
ind i de respective Branchialfodder, medens det 
andet Par synes at inneryere de Muskler, der fra 
Kroppen passerer til Basis af disse Lemmer. En 
anden betydelig svagere Nerve udspringer omtrent 
fra Midten af enhyer af Langdecommissurerne og 
synes at ende i Legemets Sidemuskler. Antallet af 
de Nerveknuder, der sammen med Commissurerne 
danner Buggangliekjeden, er paa hver Side 15 (se 
Fig: 1). Heraf er de 3 forreste Par bestemte for 
Kindbakkerne og de 2 Par Kjever, det bageste Par 
for Genitalsegmentet, de 11 ovrige for de 11 Par 
Branchialfadder. Buggangliekjeden er saaledes ind- 
skrenket til Forkroppen alene. I Bagkroppen fort- 
settes rigtignok de 2 Nervestammer. lige til Enden 
af sidste Segment, men uden her at vere forbundne 
ved Tvercommissurer og uden at danne tydelige 
Ganglier. I hvert Halesegment udsender disse Nerve- 
stammer fine Nervegrene, hvoraf nogle synes at ud- 
brede sig i Halens Muskulatur, medens andre ender 
med en liden ganglios Opsvulmning lige under Huden 
(se Fig. 8). -Paa disse Steder sees altid en over- 
ordentlig fin Borste (Foleborste) at springe frem, til- 
dels omgiyen af smaa Hudpapiller (Fig. 9). 
3 
= 
_ Angaaende den Maade, hvorpaa de ovrige Ner- 
ver ender, skal her blot omtales Forholdet med de 
til Iste Par Folere gaaende Nerver og Synsnerverne. 
" Forste Par Foleres ee udspringer. (se Fig. 4) 
at ladende fra det basale Parti af Synsnerverne, 
let. begge Nerver ved sit Udspring er omgivet af 
e les Neryeskede. De trader derefter til hver 
ey som en tynd Stamme ind i Iste Par Foleres 
Basis og fortsetter sig igjennem deres Axe indtil 
henimod | Spidsen. Her deler Nerven sig (se Fig 2) 
i 2 Grene, der tilsammen danner en betydelig gang- 
Tos Masse ved Spidsen af Foleren. Fra denne 
51 
The. ventral. ganglion chain (see fig. 1) is not 
difficult to examine, either in living specimens or in 
those preserved in diluted spirit. It is only neces- 
sary to turn the branchial 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, be seen 
clearly and distinctly, without the necessity of 
actual dissection. The front part, however, is always 
rather difficult of observation, as it is generally 
almost hidden. by the hut slightly transparent man- 
dibles: and by the maxille. The ventral ganglion 
chain. exhibits.a marked ladder-like form, in that it 
consists of 2, strong, widely-separated nerve-stems, 
which are connected in each segment by a double 
transverse commissure. Here each nerve-stem exhi- 
bits a rather slight ganglionic dilatation (see fig. 5), 
on the outer side of which, 2 strong nerves have 
their origin. One. of these pairs of nerves penetrates 
into the respective branchial 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 body. 
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 
maxille, the hindmost pair for the genital segment, 
and the remaining 11 for the 11 pairs 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 im 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 below the integument (see 
fig. 8.) At these places an exceedingly fine bristle 
(sensory bristle) is always seen to protrude, parti- 
ally surrounded by small cutaneous papille (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 antenne, and the optic 
nerves will be mentioned here. 
. The nerves of the Ist pair of antenne (see fig. 4) 
apparently originate from the basal, part of the 
optic nerves, both nerves being surrounded at their 
origin by a common neural-sheath: They then pass 
to either side. in the form of a thin stem into the 
base of the first pair of antennee, whence they con- 
tinue along the axis of the latter almost to the 
extremity. Here the nerve divides (see fig. 2) into 
2 branches, which together form a considerable 
