178 Dr. Dickinson on the Functions of the Cerebellum. [April 7, 



The removal of the cerebellum shows that the cerebrum by itself is 

 unable to give more than a limited amount of voluntary motion, and that 

 of a kind deficient in balance and adjustment. 



It is therefore inferred that the cord, together with the medulla oblon- 

 gata, is a great source of spontaneous motor power, in which function both 

 the cerebrum and the cerebellum take part, the cerebellum to the greater 

 extent ; it also appears that a certain harmony in the use of the muscles 

 depends on the possession of the latter organ. 



Regarding Fishes, the cord and medulla oblongata seem unequal to the 

 performance of voluntary motion. 



When the cerebellum is added, the powers become so far extended that 

 movements are made in obedience to external stimuli. Generally speak- 

 ing, a determined position is maintained and locomotion accomplished, 

 without the use, however, of the pectoral fins. 



If the cerebellum only be taken away, there is a loss of the proper 

 adjustment between the right and left sides ; so that oscillation or rotation 

 takes place. All the limbs are used, but apparently with a deficienc}^ of 

 sustained activity. 



It is therefore concluded that with Fishes, as with Reptiles, the power 

 of intentional movement is shared by both cerebrum and cerebellum ; the 

 former in this case has the larger influence. 



Such movements as depend on the cerebrum are destitute of lateral ba- 

 lance, are sudden in being affected by any external cause, and are emotional 

 in their character. Such as depend on the cerebellum are mutually ad- 

 justed, of a continuous kind, and less directly under the influence of con- 

 sciousness. 



The same facts were supported by experiments on the higher orders of 

 animals : in these it seemed that the cord and medulla are insufiicient to 

 excite voluntary movements. The muscles, as with fishes and reptiles, 

 acknowledge a double rule, from the cerebrum and from the cerebellum. 

 The anterior limbs are most subservient to the cerebrum ; the posterior to 

 the cerebellum. The limbs on one side are in connexion chiefly with the 

 lobe of the opposite side. The absence of the cerebellum destroys the 

 power of lateral balance. 



From the negative results of the experiments, it is inferred that the cere- 

 bellum has nothing to do with common sensation, with the sexual pro- 

 pensity, with the action of the involuntary muscles, with the maintenance 

 of animal heat, or with secretion. 



The only function which the experiments assigned to the cerebellum is 

 such as concerns the voluntary muscles, which receive therefrom a regu- 

 lated supply of motor influence. Each lateral half of the cerebellum affects 

 both sides, but the one opposite to itself most. 



The cerebellum has a property distinct from its true voluntary power, 

 which harmonizes the action of the voluntary muscles, and has been de- 

 scribed as ''coordination." 



