THE BRAIN. BAL 
iar and special share in elaborating visual impulses into visual 
sensations and perceptions; and there can be little doubt 
that the other senses are represented similarly in the cerebral 
cortex. 
The Cerebellum.— Both physiological and pathological re- 
search point to the conclusion that the cerebellum has an im- 
portant share in the co-ordination of muscular movements. 
Ablation of parts of the organ leads to disordered movements; 
and, when the whole is removed in the bird, co-ordination is 
all but impossible, and the same holds for mammals. Section 
of the middle peduncle of one side is liable to give rise to roll- 
ing forced movements. In fact, injury to the cerebellum causes 
symptoms very similar to those following section of the semi- 
circular canals, so that many have thought that in the latter 
case the cerebellum had itself been injured. 
Pathological— Tumors and other lesions frequently, though 
not invariably, give rise to unsteadiness of gait, much like that 
affecting an intoxicated person. It may safely be said that the 
cerebellum takes a very prominent share in the work of. the 
muscular co-ordination of the body. 
As has already been pointed out, several tracts of the spinal 
cord make connection with the cerebellum, and it is not to be 
forgotten that this part of the brain has, in general, most ex- 
tensive connections with other regions. Insufficient study has 
as yet been given to the cerebellum, and it is likely that the 
part it takes in the functions of the encephalon is greater than | 
has yet been rendered clear. The old notion that this organ 
bears any direct relation to the sexual functions seems to be 
without foundation. It has now been clearly demonstrated 
that the lower region of the spinal cord is, in the dog and prob- 
ably most mammals, the part of the nerve-centers essential for 
the sexual processes. 
Crura Cerebri and Pons Varolii—As has been already noted, 
the peduncles (crura) are the paths of impulses from certain 
parts of the cerebral cortex, the basal ganglia, and the spinal 
cord, The functions of the gray matter of the crura are un- 
known. But, since forced movements ensue on unilateral sec- 
tion, it is plain that they also have to do with muscular co- 
ordination. 
The transverse fibers of the pons Varolit connect the two 
halves of the cerebellum. Its longitudinal fibers have extensive 
connections—the anterior pyramids and olivary bodies of the 
medulla, the lateral, and perhaps also a part of the posterior 
