Brain and Nervous System, 65 
caterpillar, nearly eight times as many as are found in th: 
human body. The strength, too, of insects is prodigious. 
There must be quality in muscles, for muscles as large as 
those of the elephant and as strong as those of the flea 
would hardly need the fulcrum which the old philosopher 
demanded in order to move the world. Fleas have been 
made to draw miniature cannon, chains and wagons many 
hundred times heavier than themselves, 
The nerves of insects are in no wise peculiar, so far as 
known, except in position, Each nerve consists of a 
bundle of fibers some of which are sensitive and some 
motor. As in our bodies, some are knotted, or have gang- 
lia, and some are not. 
The main nervous cord is double, and has_ several 
enlargements (Fig. 16) or ganglia. It runs along the 
under or ventral side of the body, (Fig. 16), separates 
Fic. 17 
Brain of Insect, after Dujarditm 
@a Antenne. 
000 Ocelli. 
near the head, and after passing around the esophagus, 
enlarges to form the largest of the ganglia, which serves 
as a brain (Fig.17). From the brain many fibers extend 
on each side to the compound eyes. The minute nerves 
extend everywhere, and in squeezing out the viscera of an 
insect, are easily visible. 
In the larva the nerve cord is much as in the adult insect, 
except the ganglia are more numerous. Girard says, that 
at first in the larva of the bee there are seventeen ganglia. 
The supra-xsophageal or brain, three sub-xsophageal, 
three thoracic—one for each ring —and ten abdominal. 
Soon the three sub-zsophageal merge into one, as do also 
