ENCEPHALIC SEAT OF MUSCULAR MOTION. 391 



all, the functions of equilibration and progression were disordered. The 

 experiments of M. Magendie 1 on this subject, are pregnant with import- 

 ant novelty. We have already referred to those that concern the cere- 

 bral hemispheres and cerebellum as the encephalic organs of the general 

 movements, in the mode suggested by MM. Rolando and Flourens, and 

 others. M. Magendie affirms, in addition, " that there exist, in the 

 brain, four spontaneous impulses or forces, which are situate at the 

 extremity of two lines, cutting each other at right angles ; the one 

 impelling forwards ; the second backwards ; the third from right to left, 

 causing the body to rotate ; and the fourth from left to right, occasion- 

 ing a similar movement of rotation." The first of these impulses he 

 fixes in the cerebellum and medulla oblongata ; the second in the cor- 

 pora striata ; and the third and fourth in each of the peduncles of the 

 cerebellum. 



1. Forward Impulse. It has often been observed by those who have 

 made experiments on the cerebellum, that injuries of it cause animals 

 to recoil manifestly against their will. M. Magendie 2 asserts, that he 

 has frequently seen them, when wounded in the cerebellum, make an 

 attempt to advance, but be immediately compelled to run back ; and he 

 says that he kept a duck for eight days, the greater part of whose cere- 

 bellum he had removed, which did not move forwards during the whole 

 of that time, except when placed on water. Pigeons, into whose 

 cerebella he thrust pins, constantly walked and flew backwards, for 

 more than a month afterwards. Hence, he concludes, that there exists, 

 either in the cerebellum or medulla oblongata, a force of impulsion, 

 which tends to cause animals to go forward. He thinks it not impro- 

 bable, that this force exists in man ; and states that Dr. Laurent, of 

 Versailles, exhibited to him, and to the Academie Royale de Medecine, 

 a young girl, who, in the attacks of a nervous disease, was obliged to 

 recoil so rapidly, that she was incapable of avoiding bodies or pits 

 behind her ; and was, consequently, exposed to serious falls and bruises. 

 This force, he affirms, exists only in the mammalia and birds ; certain 

 fish and reptiles, on which he experimented, appearing to be unaffected 

 by the entire loss of the cerebellum. 



2. Backward Impulse. M. Magendie found, 3 when the corpora stri- 

 ata were removed, that the animal darted forward with great rapidity ; 

 and, if stopped, still maintained the attitude of running. This was particu- 

 larly remarked in young rabbits ; the animals appearing to be impelled 

 forward by an inward and irresistible power, and passing over obstacles 

 without noticing them. These effects were not found to take place, 

 unless the white, radiated part of the corpora striata was cut : if the 

 gray was alone divided, no modification was produced in the movements. 

 If only one of the corpora was removed, the rabbit remained master of 

 its movements, directed them in different ways, and stopped when it 

 chose ; but, immediately after the removal of the other, all regulating 

 power over the motions appeared to cease, and it was irresistibly im- 

 pelled forwards. In the disease of the horse, called, by the French, 



, the animal is often capable of walking, trotting, and gallop- 



Op. citat., i. 345. 2 p^cis, i. 341. 3 Op. cit., i. 337. 



