MUSCULAR MOTION. 



the results of his experiments, which showed, that the movements 

 diminished in proportion to the injury done to the cerebellum, Rolando 

 drew the inference, that this part of the encephalon is an electro-motive 

 apparatus for the secretion of a fluid analogous to the galvanic. This 

 fluid is, according to him, transmitted along the nerves to the muscles, 

 and excites them to contraction. The parts of the encephalon con- 

 cerned in volition would, in this view, regulate the quantity in which 

 the motive fluid is secreted ; and govern the motions ; whilst the medulla 

 oblongata, which, when alone irritated, always occasions convulsions, 

 would put the encephalic extremity of the conducting nerves in direct 

 or indirect communication with the locomotive apparatus. 



This ingenious and simple theory is, however, far from being corro- 

 borated, by the fact, mentioned by M. Magendie, 1 that he is annually in 

 the habit of exhibiting to his class animals deprived of cerebellum, 

 which are capable of executing regular movements. For example, he 

 has seen the hedgehog and Guinea-pig, deprived not only of brain but 

 of cerebellum, rub the nose with its paw, when a bottle of strong acetic 

 acid was held to it ; and he remarks, that a single positive fact of the 

 kind is worth all the negative facts that could be adduced. He farther 

 observes, that there could be no doubt of the entire removal of the 

 brain in his experiments. The experiments of Magendie are, however, 

 equally adverse to the hypothesis of M. Flourens, that the cerebellum 

 is the regulator or balancer of the movements. Some anatomical ob- 

 servations by Mr. Solly 2 would seem to show, that there is a direct 

 communication between the motor tract of the spinal marrow and the 

 cerebellum. The corpora pyramidalia have been generally supposed 

 to be formed by the entire mass of the anterior or motor columns of the 

 spinal cord, but Mr. Solly shows, that not more than one-half of the 

 anterior column enters into the composition of these bodies ; and that 

 another portion, which he terms " antero-lateral column," when traced 

 on each side in its progress upwards, is found to cross the cord below 

 the corpora olivaria, forming, after mutual decussation, the surface of 

 the corpora restiformia; and being ultimately continuous with the cere- 

 bellum. 



Others, again, have estimated the encephalon to be the sole organ 

 of volition, and have referred the nervous action, which produces the 

 " locomotive influx," as it is termed, exclusively to the spinal marrow; 

 and hence they have termed the spinal marrow, and the nerves issuing 

 from it, the "nervous system of locomotion." It is manifest, however, 

 that the encephalon must participate with the medulla spinalis in this 

 function ; inasmuch as not only does direct irritation of several parts 

 of the former excite convulsions, but we see them frequently as a con- 

 sequence of disease of the encephalon; yet, as has been remarked, 

 there is some reason for believing, that, in the upper classes of animals, 

 an obscure volition may be exercised for a time, even when the ence- 

 phalon is separated from the body. It need scarcely be said, that we 



1 Precis, &c., i. 340. 



7 - Transactions of the Royal Society for 1836 ; and Solly on the Brain, Araer. edit., Phila., 

 1848. 



