No. 388.] MAINTENANCE OF THE EQUILIBRIUM. 321 
cerebellum, and some of them pass entirely into it. No con- 
nections between the nerve fibres arising’ from the labyrinth 
and the cerebrum are known, but the labyrinth has many direct 
and indirect nervous connections with the cerebellum. 
It is found, therefore, that, with the exception of the optic 
nerve, all those sensory tracts which are used in equilibration 
collect in the cerebellum. And there certainly are connectives 
between the optic nerve and the cerebellum, yet in regard to 
this our knowledge is very incomplete. These are the purely 
anatomical considerations which point to the cerebellum as the 
center of codrdination or equilibration. But physiological experi- 
ment also shows us facts which lead to the same conclusion. 
Only a carefully performed and rightly interpreted experi- 
ment can inform us as to the function of this part of the brain. 
Erroneous observations and interpretations have ascribed to 
the cerebellum all possible functions; for example, the seat of 
the soul, the emotions, the memory, and so forth, 
If one wound the cerebellum of an animal badly, or if he 
extirpate a portion of it, there is no proper regulation of the 
muscular contractions, and there is a decided disturbance of- 
the equilibrium, resulting from the defective innervation of: the 
muscles. An animal thus treated makes the most senseless 
and inopportune motions without accomplishing its purpose ; 
yet it hears and sees, and its intelligence appears not to be 
interfered with. 
Similar phenomena occur in men having diseases of the cere- 
bellum. As we shall return to this point again, I will here only 
briefly note that, in most cases of serious disease of the cere- 
bellum, disturbances of the equilibrium and dizziness are present. 
We have found, to summarize the above, not absolutely cer- 
tain proof, but still a number of important reasons which fully 
justify us in searching in the cerebellum for the central appa- 
ratus for muscular coérdination, and the resulting preservation 
of equilibrium. 
Thus we have solved a part of the problem presented to us. 
We can now represent diagrammatically (Fig. 2) the whole appa- 
ratus which must take part in the process of equilibration. To 
the cerebellum (4) there are transmitted various sensations 
