Chap, ii.] THE BRAIN. 813 



starting largely from the nucleus dentatus, affords another 

 connection with the cerebrum, largely crossed, though possibly 

 partly uncrossed; but this is an indirect connection so far as the 

 cerebral cortex is concerned, since the peduncle ends in the red 

 nucleus and other tegmental structures. This connection is 

 presumably the channel of impulses passing from the cerebellum 

 to the cerebrum ; but we can only say ' presumably.' 



The above connections are too complex to enable one to 

 draw from them any precise physiological deductions ; and when 

 we turn to the results of experiment and clinical observation, 

 we find even these by no means clear. 



Electrical stimulation of the surface of the cerebellum, in the 

 monkey and in other animals, has led to movements of the eyes, 

 and of other parts of the head ; but we cannot from such results 

 draw any satisfactory inferences. 



The results of removing either portion of or the whole of 

 the cerebellum have been partly accordant, partly discordant. 

 They agree in shewing that the organ has no special connections 

 with the sexual functions, a view once largely held. They also 

 appear to agree in so far that the effects produced by removing 

 a lateral half are largely if not wholly confined to the same side 

 of the body ; the influence exerted by one half of the cerebellum 

 tells on one half of the body, and that on the same side. They 

 further agree in that removal of even the whole of the cerebellum 

 has no obvious psychical effects, and does not appear to interfere 

 with the full development of cutaneous and other sensations. 

 Lastly, while they agree in indicating that the cerebellum plays 

 a special part in the coordination of movements affecting equil- 

 ibrium, and this is also shewn by clinical histories, they are not 

 agreed as to how that part is exactly played. 



The effects produced by removal of the cerebellum are in 

 part immediate and temporary, in part of a more lasting char- 

 acter. Characteristic among the former are some of the 'forced 

 movements ' treated of in § 480, such, for instance, as rotation 

 round the longitudinal axis of the body; this seems especially 

 to occur after division of the middle peduncle. And the move- 

 ments of the body in general are for a while in a remarkable 

 degree incoordinate and irregular, so that locomotion and even 

 the maintenance of a natural attitude are for the time impossible. 

 Tonic spasms of various muscles are also observed, those of the 

 trunk leading to curvature of the body. Later on this condition 

 subsides, but there remains as a lasting effect an imperfection 

 of movement, an unsteadiness of gait, an irregularity and short- 

 coming in muscular actions, accompanied frequently by mus- 

 cular tremors. This unsteadiness in movement is also seen in 

 many cases of cerebellar disease, the gait of the patient in many 

 respects resembling that of a person who is drunk. Obviously 

 the cerebellum has some important influence over the contrac- 



