OF INSECTS. 
179 
acic ganglia are nearly united into one mass ; and all 
the nerves furnished by these ganglia to the loco- 
motive organs, will he seen to have acquired a con- 
siderable development. 
The sympathetic nervous system has been known 
from the time of Swammerdam, who discovered it in 
the larva of the rhinoceros-beetle (Oryctes Nasicor- 
nis } ) hut its real nature, and the analogy it bears to 
the great sympathetic nerve of the vertehrata, were 
not understood till it was made the subject of a 
special investigation by John Muller .* It exists 
more or less distinctly in all articulated animals, but 
in none is it so complete as in insects. It is con- 
sidered as forming two divisions ; one of them con- 
sisting of a single cord, running along the anterior 
portion of the alimentary canal, and emitting delicate 
filaments on each side ; the other of a double nervous 
web, originating on each side by one branch from the 
posterior portion of the anterior cephalic ganglion, 
running down the esophagus, and sending forth 
branches to the single nervous cord. Both these 
divisions stand in the most intimate relation to each 
other, and form one continuous system. The first 
is most conspicuous in Coleoptera, Neuroptera, and 
Lepidoptera. In these it takes its rise in tw T o arched 
branches from the anterior cephalic ganglion, which 
unite in the centre and form a small knot, from which 
a single nerve emanates and runs beneath the cere- 
brum. From its curved shape, this was called by 
Nova Acta Phys. Med. Soc. XI Y. part 1, p. 73. 
