SUMMARY OF STRUCTURES 247 



much more humanoid than those ol the still lower primates. Although 

 it is distinctly subhuman in its manual achievements, none the less 

 mycetes must be assigned a place well up in the class of delinite manual 

 ditlerentiation. 



II. The Inferior Olivary Nucleus in Relation to the Regulation 

 OF Movements in the Eves, Head and Hands 



FUNCTION of the INFERIOR OLIVARY NUCLEUS 



There is considerable doubt concerning the function of the inferior 

 olivary nucleus. Certain facts regarding it, however, are fairly obvious. The 

 olive must be closely related in function to the cerebellum since its major 

 connections are with that organ. The axons arising in the olivary substance 

 pass as olivo-cerebellar fibers to the inferior cerebellar peduncle and thus 

 reach the vermis and lateral cerebellar lobes. Whatever the precise function 

 of this structure may be, its intimate association in the cerebellar reflex arc 

 implies an activity related to the coordinative control of somatic muscula- 

 ture. The inferior olive is intercalated as a relay nucleus in some important 

 pathway whose impulses are destined to the cerebellum. It apparently serves 

 to diffuse these impulses more extensively and thus bring into operation 

 larger fields of cerebellar tissue in the interest of a highly specialized coordinat- 

 ing activity. 



Von Bechterew and other neurophysiologists are largely agreed that the 

 inferior olive is functionally concerned with static coordination. Experiments 

 upon dogs in which the olive of one side has been injured cause a peculiar 

 paralysis of the eye muscles with irregular nystagmic movements and 

 simultaneous torsion of the body about its long axis. This torsion immedi- 

 ately follows the injury and attains its highest degree directly after the 

 operation. In the course of time the torsion becomes less pronounced and the 

 paralysis of the eye muscles together with the nystagmus diminishes. 



