INSECTA. 



271 



The brain, or encephalic ganglion (Jig. 121, 1), is a nervous 

 mass of considerable size placed above the gullet ; it consists es- 



Fig. 121. 



sentially of two ganglia united into one mass, and from it all the 

 nerves appropriated to the special instruments of the senses are de- 

 rived, so that it may naturally be regarded as the chief seat of sens- 

 ation and intelligence. The nerves originating from this common 

 sensorium are seen upon an enlarged scale in Jig. 122 : they are the 

 optic (Jig- 122, a), supplying the eyes, and the antennal (Jig. 

 122; e), which run to the special instruments of touch, or antenna',, 



