FORCED MOVEMENTS 567 



it is because the power of such harmonious movement would be equally lost, whether the 

 injury to the cerebellum involved injury to the seat of muscular sense or to the center 

 for combining muscular actions, that experiments on the subject afford no proof in one 

 direction more than the other. 



Forced Movements. The influence of each half of the cerebellum 

 is directed to muscles on the opposite side of the body; and it would appear 

 that, for the right ordering of movements, the actions of its two halves must be 

 always mutually balanced and adjusted. For if one of its crura, or if the 

 pons on either side of the middle line, be divided, so as to cut off from the 

 medulla oblongata and spinal cord the influence of one of the hemispheres 

 of the cerebellum, strangely disordered movements ensue forced movements. 

 The animals fall down on the side opposite to that on which the crus cerebelli 

 has been divided, and then roll over continuously and repeatedly; the rotation 

 being always round the long axis of their bodies, and generally from the side 

 on which the injury has been inflicted. The rotations sometimes take place 

 with much rapidity; as often, according to Magendie, as sixty times in a min- 

 ute, and may last for several days. Similar movements have been observed 

 in men; as by Serres in a man in whom there was apoplectic effusion in the 

 right crus cerebelli; and by Belhomme in a woman in whom an exostosis 

 pressed on the left crus. They may, perhaps, be explained by assuming that 

 the division or injury of the crus cerebelli produces paralysis or imperfect and 

 disorderly movements of the opposite side of the body; the animal falls, and 

 then, struggling with the disordered side on the ground, and striving to rise 

 with the other, pushes itself over; and so again and again, with the same act, 

 rotates itself. Such movements cease when the other crus cerebelli is divided; 

 but probably only because the paralysis of the body is thus made almost com- 

 plete. Other varieties of forced movements have been observed, especially 

 those named "circus movement," when the animal operated upon moves 

 round and round in a circle; and again those in which the animal turns over 

 and over in a series of somersaults. Nearly all these movements may result 

 on section of one or other of the following parts: viz., crura cerebri, medulla, 

 pons, cerebellum, corpora quadrigemina, corpora striata, optic thalami, and 

 even, it is said, of the cerebral hemispheres. 



V. THE CEREBRUM. 



That portion of the brain which is concerned with all intellectual functions 

 is the cerebrum or, more strictly speaking, the cerebral cortex. The cerebral 

 cortex is the seat of those activities which we describe as intelligence 

 including states of consciousness, acts of idea formation and volition, and 

 the phenomenon of memory. 



The cerebrum includes the cerebral cortex, the mass of fibers connecting 

 it with lower portions of the brain, the basal nuclei represented by the corpora 



