66 
CHAPTER XL 
THE BRAIN. 
Instinct — httelligence — Supra^ocsophageal Ganglion — Examina- 
Hon of Brain — Convolutions — Pedtmculated Bodies — Relation 
of Size of Pedunculated Bodies to hztelligence — CoznparisoH of 
Size of Braizt of Various Insects — Brain STUaller in Queezis 
and Drones. 
It was supposed that insects incapable of collecting 
ideas were only actuated by instinct, and that this 
had its origin equally in each of the ganglia, more 
especially as it was found that a decapitated insect con- 
tinued to run and move, and made an endeavour to 
regain its feet if turned over. Dujardin (33) also 
mentions several examples which show that voluntary 
movements can be produced to a certain extent after 
decapitation. For instance, a large fly {etlstalis tenax) 
which had its head cut off and prevented from drying, 
after between eight and nine hours continued to fulfil 
its digestive functions, move its wings, its legs, and 
ovipositor, under the influence of the sun’s rays, and 
when the meta-thorax was touched it immediately 
brought forward its hind legs to remove the strange 
object, or to clean and rub its wings; at the same 
time the tongue was protruded from the separated 
head to suck the liquid presented to it. All these, 
however, are purely instinctive movements, actuated 
by the ganglia, as are those which produce the move- 
ments of the sting in a bee or wasp after the 
abdomen is cut off from the other part of the body. 
