THE NERVOUS SYSTEM 



383 



perch, we see in front a pair of olfactory lobes (which 

 send forth the nerves of smell), behind them the small 

 cerebral hemispheres, then the large optic lobes (near 

 which originate the nerves of sight), and, last of all, the 

 cerebellum. Not until we reach man and the apes do 

 we find the cerebrum so highly developed as to overlap 

 both the olfactory lobes in front and the cerebellum 

 behind. 



Functions of the Brain. The cerebrum is the seat of 

 intelligence and will. It has no direct communication 

 with the outside world, receiving its consciousness of 

 external objects and events through the spinal cord and 

 the nerves of special sense. 140 



The cerebellum seems to preside over the coordina- 

 tion of the muscular movements. When the cerebellum 



FIG. 338. A, C, upper and side views of the Brain of a Lizard ; B, D, upper and side 

 views of the Brain of a Turkey: Olf, olfactory lobes ; Hmp, cerebral hemispheres ; 

 />, pineal gland ; Mb, optic lobes of the middle brain ; Cb, cerebellum; MO, me- 

 dulla oblongata ; it, optic nerves; iv and vi, nerves for the muscles of the eye ; 

 Py, pituitary body. 



is removed, the animal desires to execute the mandates 

 of the will, but can not ; its motions are irregular, and it 

 acts as if intoxicated. It is usually largest in animals 

 capable of the most complicated movements, being 



