Central Nervous System of a Centipede 
ARTHUR S. CAMPBELL 
The central nervous system of 8. Polymorpha Woods, is especially studied in the 
present paper. 
Hymonds (1898) considers the development giving especial note to the homologies 
of this system. Newport (1843) gives some notes in regard to the brain. Saint-Remy 
(1890) gives considerable detail especially in regard to the finer structure of the 
brain of S. Morsitans L. Case (1920) has shown something of the behavior of 
S. Polymopha and indirectly the arrangement of never tracts. 
Ordinary dissections and the occaasional‘use of a binocular microscope proved 
the most useful. 
pee ak 
Successful stains were Heidenhewn’s and Delafield’s Haemttoylins. HgCl. or 
AgNOs seemed the best fixers. Tracheae were studied without a is immediately 
after exposure. 
In S. Polymorpha the supraoesophagal ganglion or brain comprises three paired, 
fused divisions or lobes. Large branches extend from the antennal lobes into the 
antennae. The ocular lobe fuses with this and is distinctly larger and less markedly 
bilobate. This lobe sends out nerves to the oceili. The labro-fontal division is under- 
neath the ocular lobe and entirely fused with it. It innervates the labrum. 
The supraoesophageal ganglion in S. Polymorpha is large. It is anteriorally 
connected with the brain by two circumoral connectives. Ten principal, paried 
herves are connected with this ganglion. The anterior pair extend into the mandibles. 
The second pair supplies the first maxillae, the third runs to the second maxillae. The 
fourth pair innervates the maxillipeds. The fifth pair supplies the prehensorial 
feet. 
The remaining somites are supplied by simple, similar ganglia, equally spaced 
but well separated by connectives. The third and fourth ganglia area almost fused, 
due to the foreshortened segments in which they are located. There is no histological 
difference between them and other abdominal ganglia. One ganglion only is present 
in each somite. Altogether in S. Polymorpha there are twenty-four ganglia. 
Each abdominal ganglion gives off eight nerves. There is no ventral nerve. The 
first pair of branches supplies the tergular muscles, the second the walking legs, the 
third the sternal muscles and the fourth supplies the spiracles and tracheae. 
The two caudal ganglia present special interest. Four principal branches run 
from the first of these. The first supplies the tergal muscles, the second the sternal 
muscles while the fourth supplies the anal legs. Additionally, two preanal connectives 
join with a small ganglia about half the normal size of the others. Four nerves 
extend from this last small ganglion into the sphincter and other anal muscles. 
In general the superficial tracheal distribution is rather definite. and much 
resembles that of the insects. The brain is rather poorly supplied by but two main 
tracheae on either side which break up into a number of tracheoles which -run into 
the antennae and optic lobes. In contrast to this, the suboesophageal ganglion is 
supplied dorsally by three tracheaae on each side. 
