70 APPENDIX. 



fto have established this proposition in a satisfactory manner, with regard to the senses of 

 sight and hearing 1 ; tor when both lobes of the cerebrum are removed, th animal becomes 

 both blind and deaf. Instead of saying, with M. Flourens, that the cerebral lobes 

 are the only organs of sensation, we should restrict ourselves to ascertain facts, and con- 

 tent ourselves with saying that these lobes are the sole receptacle where the senses of 

 sight and hearing can be perfected, and become perceptible to the animal. If we 

 wished to add to this, we should say that they are likewise those where all the sensa- 

 tions take a distinct form, and leave durable traces on the memory, that they serve, in 

 a word, as the seat of memory ; a property, by means of which they furnish the animal 

 materials for judgment. This conclusion, thus reduced to proper terms, becomes the 

 more probable, in that, besides the veri-similitude which it receives from the structure 

 of these lobes, and their connexion with the rest of the system, comparative anatomy 

 offers another confirmation in the constant relation of the volume of these lobes with 

 the degree of intelligence of the anmal." 



M. Flourens next examined the effects which follow the extirpation of the tubercnla 

 quadrigemina. " The removal of one of them, after a convulsive movement, which 

 soon ceases, produces, a permanent result, blindness of the opposite eye and involun- 

 tary staggering ; that of both tubercles renders the blindness complete, and the stag- 

 gering more, violent and long-continued. The animal, however, retains all its faculties 

 und the iris continues contractile. Tho deep extirpation of the tubercle, or the sec- 

 tion of the optic nerve only, paralyses the iris : from which the author infers, that 

 the the removal of the tubercle only acts as the division of the nerve would do ; that 

 this tubercle is only a conductor uith regard to vision ; and that the cerebral lobe alone 

 Is the seat of the sensation, the point where it is consummated, and passes into per- 

 ception." 



M. F. next investigated the functions of the cerebellum,, and found that, during the 

 removal of the first layers, " there appeared only a slight weakness and want of har- 

 mony among the movements. At the middle layers, a disturbance nearly general was 

 manifested. The animal, in continuing to see and hear, only executed quick and ir- 

 regular movements : the faculty of flying, walking, and keeping itself standing, were 

 lost by degrees. When the bra'in was cut off, this faculty of performing regulated mo- 

 tion had entirely disappeared. Placed upon the back, he did not rise ; but continued 

 to see the blow which menaced him ; he heard sounds, and endeavoured to shun the 

 danger which was threatened : in a word, feeling and volition were retained, but the 

 power over the muscles was lost; scarcely could he support himself with the assistance 

 of the \yings and tail. In depriving the a'nimal of the bruin, it was thrown into a state 

 resembling sleep : in removing the cerebellum, it was brought to a state resembling 

 intoxication." 



The reporters to the Institute on the inquiries of M. Flourens, have drawn the fol- 

 lowing conclusions " from a rigorous examination of the facts which he has establish- 

 ed : the integrity of the cerebral lobes is necessary to the exercise of sight and hear- 

 ing : when they are removed, the will no longer manifests itself by voluntary acts. 

 However, when the animal is immediately excited, he performs regular movements, as 

 if endeavouring to avoid pain or inconvenience ; but these movements do not effect his 

 purpose, most probably because the memory, which has been removed along with the 

 lobes which constituted its seat, no longer affords grounds or elements of judgment : 

 Ihese movements have no consistency, for the same reason, that the impulse which 

 caused them neither leaves any remembrance nor permanent volition. The in- 

 tegrity of the cerebellum is necessary to the regularity of locomotion : let the brain 

 remain, the animal will see, hear, and have evident and powerful volition ; but, if the 

 cerebellum be removed, he will never find the balance necessary to locomotion. As 

 to the rest, irritability remains in parts without the brain or cerebellum being neces- 

 sary. Every irritation of a nerve brings it into play, in muscles to which it is distribut- 

 ed : every irritation of the spinal marrow excites ft in all members beneath the point 

 of its application. It is quite at the top of the medulla obhwgata, at the point where the 

 tubercula quadrigemina join it, that this faculty of receiving and propagating irrita- 

 taion on the one hand, and pain on the other, ceases. It is this point at which sensa- 

 tion must arrive in order to be perceived ; it is from hence that the mandates of the 

 will must emanate. Thus, the continuity of the nervous organ from this point to the 

 different parts of the body is requisite for voluntary motion, and for the perception of 

 impressions whether external or internal." 



Thus, then, the property of nervous irritability or of receiving and conducting sensa- 

 tion and irritation is limited to the nerves, spinal cord, medulla oblongata, and corpora 

 quadrigemina, " the integrity of the optic thalami is not essential to the contractility 

 of the iris ; the sensations of light and of sound reside in th~ cere-bra! lobes, and therv 



