J 823.] Powers of the Brain developed. 247 



that therefore lie Las not experienced Placed upon its back, tlic animal no longer 



them. Hence, the ccrehrul lobes are the turned itself: it nevertheless perceived the 



sole organs of sensation, or these lobes are blow with which it was menaced ; it heard 



the only receptacle in which the sensations cries, and endeavoured to avoid danger by 



of sight and hearing can be perfected, and a thousand frnitless efforts : in a word, it 



become perceptible to the animal. They retained its faculties of sensation and voli- 



are also the receptacle in which the sensa- tion, but h^d lost the power of producing 



lions assume a distinct form, and leave du- voluntary muscular contractions. It was 



fable impressions on the memory; that scarcely able to keep its erect position, by 



they are in fact the seat of memory, the supportin;^ itself with its wings and tail. 



faculty by which they furnish the animal 

 with the materials of judgment. This 

 conclusion, reduced to its exact and pro- 

 per terms, would become the more proba- 

 ble, since, beside the probability it derives 



1 he extirpation of the brain bad pro- 

 duced a state of sleep ; the excision of 

 the cerebellum produced one of in- 

 toxication. 



" It is astonishing," says M. Flourens, 



from the structure of the cerelrral lobes, " to observe the pigeon losing by degrees, 



and their connexions with the rest of the 

 system, it is still further supported by a 

 fact in comparative anatomy, tliat the 

 intelligence of animals is constantly 

 proportioned to the volume of these 

 lobes. 



Having observed the effects of the abla- 

 tion of what n)ay be strictly called the 

 brain, M. Flourens pi-oceeds to examine 



as its ccrchellum is removed, the faculty of 

 flying; then, that of walking; and, lastly, 

 that of holding itself in thenpright posture 

 — and this, also, is only gradually lost. 

 The animal begins to be incapable of re- 

 maining erect upon its legs ; then its feet 

 become unable to sustain it. At last 

 every fixed position becomes impossible: 

 it makes incredible efforts to attain some 



those of the extirpation of the tubercula particular posture, without being able to 

 quadiigemina. The excision of one of accomplish it ; and yet, when exhausted by 



these luberclps, after a convulsive motion 

 of short duration, produces a durable bhud- 

 iiess of the eye on the opposite side, and 

 an involuntary giddiness ; tliat of both 

 tubercles, renders the blindness more 

 complete and the giddiness more violent 

 and prolonged. The animal, however, re- 

 mains in possession of its other facnlties, 

 and the iris retains its contractility. The 

 deep extirpation of the tubercle, or the 

 section of the optic nerve, produces only 

 paralysis of the iris ; whence M. Flourens 

 concludes, that the ablation of the tubercle 

 lias no other effect than would follow the 

 section of the nerve ; that the tubercle, 

 therefore, is only a conductor of vision ; 

 and that the cerebral lobe alone is the 

 term of the sensation of sight, and the 

 place in which it is completed, by being 

 converted into a perception. He ob- 

 serves, that, when the extirpation of the 

 tubercles is too deeply performed, the 

 medulla vblousntu is atiected, and gives rise 

 to violent and continued convulsions. 



The most curious and novel part of the 

 experiments of M. Flourens seems to us to 

 be that which concerns the functions of the 

 cerebellitm. 



During the ablation of the first laminaB, 

 he observed iiolhing more than a slit;ht 

 weakness, and a want of connexion in the 

 motions of the animal. When the inic'dle 

 laminae wtie removed, a nearly general 

 agitation was manifested. The animal, 



fatigue, it seems desirous of obtaining some 

 repose, its senses are so clear, that the 

 least gesture of the operator produces a re- 

 commencerarnt of its contortions, without 

 the slightest convulsive motion, so long as 

 the tubercula or the medulla oblongata re- 

 main uninjured." 



We are not aware that any physiologist 

 has hitherto produced any experiments 

 which exhibited (he slightest resemblance 

 to these singular plianomena. Experi- 

 ments on the cereliclium of quadrupeds, 

 especially if adult, are extremely difficult, 

 on account of the thick bony paiietes 

 which it is necessary to remove, and the 

 large vessels which are unavoidably 

 opened. Besides, most experimenters 

 have conducted their operations accord- 

 ing to some established system, and 

 have been too apt to find that which they 

 wiilied to discover; and, assuredly, none 

 have hitherto surmised that the organ which 

 biihincis and regulaUs the motions vf progres- 

 sioti, tens the cerebellum. 



Theintesrity of the arehrum is, therefore, 

 indispensable for the exercise of sight and 

 hearing : when tlicy are destroyed, the 

 will is no longer manifested by acts of 

 spontaneous volition. Nevertheless, if the 

 animal be excited from without, it exe- 

 cutes regular acts of locomotion, as if en- 

 deavouring to avoid the immediate pain 

 and inconvenience. But these motions 

 are inadequate to the end ; very probably 



though still s' eing and liearin-;, performed because the memory, which disajipcared 



motions only in an uncertain and hasty 

 manner. Its faculty of fljing, walking, 

 and relaininc the erect posture, was gradu- 

 ally lost. When the cerebellum was re- 

 moved altogether, the faculty of perform- 

 iag regulated mo'.ious entiiely ceased. 



with the removal of the lobes which seem 

 to be its scat, no longer supplies the basis 

 or elements of judgment. For the same 

 reason, these motions are followed by no 

 decisive result; because the impression 

 wliich produced them leaves no trace on 



the 



