426 ANATOMY AND PHYSIOLOGY OF THE BRAIN. 



parts higher up, while the inferior portion is the conductor 

 of volitional force. 



As a nervous centre, it seems to preside to some extent 

 over some cranial nerves, such as the facial and abducens, 

 which are connected with ganglia in its substance. It 

 seems, besides, to be the first cerebral centre in which any 

 power of sensation resides. This is proved by the experi- 

 ments of Flourens and Longet, in which, after removal of 

 the cerebral hemispheres, cerebellum, optic thalami, corpora 

 striata, and corpora quadrigemina, so as to leave nothing 

 but the pons and medulla, the animal still cried out on its 

 tail being pinched, and raised its paw to its nose when that 

 part was irritated by ammonia. The subject sought to lie 

 in an easy posture, and if disturbed immediately resumed 

 it. When left alone, the animal invariably remained quite 

 passive and motionless. When the pons itself was removed, 

 no further response was made on the application of an 

 irritant, but the creature remained quite dead to surrounding 

 things, the only vital movements retained being those of 

 the respiratory and circulatory processes. 



The functions of the cerebellum are by no means well 

 understood. It has been held by Gall and Spurzheim, that 

 it presides over the reproductive function, and varies in 

 size according to the activity of the latter. Facts, however, 

 rather oppose this theory. Many animals which are noto- 

 riously salacious, as kangaroos and monkeys, have compa- 

 ratively small cerebelli, and the relative weights of this 

 organ in entire and castrated horses point in the same 

 direction. M. Leuret took the weight of the cerebellum 

 absolutely, and as compared with that of the cerebrum, in 

 ten stallions, twelve mares, and twenty-one geldings. The 

 result of the absolute weights is given in the following 

 table : 



