REPORT ON THE PHYSIOLOGY OF THE NERVOUS SYSTEM. 71 



the left side. Hence it appears that section of the crus lias 

 more influence over the lateral rotation of the hotly than injury 

 of the cerebellum itself; and that the impulsive force does not 

 belong (at least exclusively) to the cerebellum. Wlien the cere- 

 bellum was divided precisely in the median line, the animal 

 seemed suspended between two opposing forces, sometimes in- 

 clining towards one side, as if about to fall, and again thrown 

 suddenly back to the opposite side. Its eyes were singularly 

 agitated, and seemed about to start from the orbits. Similar 

 movements followed division of the continuous fibres in the 

 pons Varolii. Serres has described a case of similar rotatory 

 motion occurring in the human subject. A shoemaker ha- 

 bituated to excess in alcoholic liquors, after great intemperance 

 was seized with an irresistible disposition to turn round upon 

 his own axis, and continued to move so till death ensued. On 

 inspecting the brain, one of the crura cerebelli was found much 

 diseased, and this was the only alteration of structure visible 

 in any part of the nervous system. 



M, Flourens has published in a recent volume of the Me- 

 moir es de VAcad^mie des Sciences* a description of some 

 striking abnormal motions which followed the division of the 

 semicircular canals of the ears of birds. Though these organs 

 have no anatomical relation to the cerebrum or cerebellum, the 

 altered motions resulting from their division are so analogous 

 to those observed by Magendie after lesions of the corpora 

 striata and crura, that they may be most conveniently described 

 in the same section. Two of the semicircular canals are ver- 

 tical, and one horizontal. Division of the horizontal canals on 

 each side occasioned a rapid horizontal movement of the head 

 from right to left, and back again, and loss of the power of 

 maintaining an equilibrium, except when standing, or when 

 perfectly motionless. There was also the same singular rota- 

 tion of the animal round its own axis which follows injury of 

 the crura cerebelli. Section of the inferior vertical canal on 

 both sides produced violent vertical movements of the head, 

 with loss of equilibrium in walking or flying. There was in this 

 case no rotation of the body upon itself, but the bird fell back- 

 wards, and remained lying on its back. When the superior 

 vertical canals were divided, the same phenomena were ob- 

 served as in section of the inferior, except that the bird fell 

 forward on its head, instead of backward. All the canals, both 

 vertical and horizontal, having been divided, in another pigeon, 

 violent and iwegular motions in all directions ensued. When, 



* torn. ix. p. 454. 



