THE ANALYSIS OF BEHAVIOUR 



147 



know relatively little of the nerve tracts in the brains of the 

 amphibia, reptiles, and birds), we may consider the conditions 

 in man. We have already indicated the connections between the 

 cord, cerebellum, mid-brain, and cortex, but a purely schematic 

 figure will be useful. Fig. 44, then, represents the main com- 

 munications between the mid-brain and spinal cord. The parts 



control 



CORTEX 



nerves 



IfferenT 

 Cranial 



muscles of head 



Afferent 



sfiina I 



nerves 

 general bodily sensation 



Efferentl 

 Spina I 1 



nerves 

 muscles of body, 



THALAMl 



ft I'D -BRAIN 

 MEDULLA 



B 



SPINAL 

 CORD 



\--general 



sensibility 

 in muscles 



'-T > ain i heat i cold Touch 

 ~ flu scu la r control 



FIG. 45. MAIN PATHS IN THE NERVOUS SYSTEM AS A WHOLE. 



below the line, AB, we regard as the simple, primitive, 

 central, nervous system, such as it probably was in the ancestors 

 of the vertebrates, while the parts above AB represent the addi- 

 tional connections established when the great sense organs of the 

 head have become evolved. In Fig. 45 we add the mechanisms 

 involved in the cerebellum and cerebral hemispheres. 



