82 Instinct and Intelligence 



The fore-brain in insects is formed by the 

 optic ganglia together with two masses of 

 nervous substance united by communicating 

 fibres. In connection with these lobes we find 

 aggregations of small granule nerve cells from 

 which fibres pass to the mid-brain. Similar 

 masses of nerve cells exist in the brain of the 

 sea-mouse, and are more highly developed in 

 crayfish (Fig. n, G.N.), but they attain their 

 highest state of perfection in insects. For 

 instance, in the working bee nervous structures 

 of this description form two masses, situated 

 near the dorsal surface of the brain. Within 

 the same order of beings these structures 

 increase in size in proportion to what we judge 

 to be the instinctive capabilities of the animal, 

 they are larger in the worker than in the drone 

 or the queen bee. 1 



The mid-brain or antennary lobes of insects 

 consist of two masses of nerve cells united by 

 bands of communicating fibres. From this part 

 of the brain nerves pass to the antennae; it is 

 also the meeting-place of nerve fibres proceed- 



1 Mr. R. H. Burne, Catlg. Phys. Series of Compa. Anatomy, 

 Royal Col. Surgeons Museum, p. 35. 



