REPORT ON THE PHYSIOLOGY OF THE NERVOUS SYSTEM. G5 



the morbid actions consequent upon such serious injuries, and 

 to distinguish the secondary and varying phenomena, induced 

 by the pressure of extravasated blood, or the spread of an in- 

 flammatory process, from those which are essential and pri- 

 mary. The ablation of small and completely insulated portions 

 of brain must, then, be classed among the " agenda" of experi- 

 mental physiology. 



The most decisive researches, that have been hitherto insti- 

 tuted on the functions of the brain, are those of M. Flourens. 

 His mode of o^ierating was to remove cautiously successive thin 

 slices of cerebral matter, and to note the corresponding changes 

 of function. He commenced with the hemispheres of the brain, 

 which he found might be thus cut away, including the corpora 

 striata and thalami optici, without apparently occasioning any 

 pain to the animal, and without exciting convulsive motions. 

 Entire removal of the cerebrum induces a state resembling coma ; 

 the animal appears plunged in a profound sleep, being wholly 

 lost to external impressions, and incapable of originating mo- 

 tion ; it is deprived, too, according to Flourens, of every mode 

 of sensation. Hence the cerebrum is inferred to be the organ in 

 which reside the faculties of perception, volition and memory. 

 Though not itself sensible, in the ordinary acceptation of the 

 word, — that is, capable, on contact or injury, of propagating sen- 

 sation, — yet it is the point where impressions made on the ex- 

 ternal organs of sense become objects of perception. This ab- 

 sence of general sensibihty observed in the brain has also been 

 experimentally demonstrated in the nerves dedicated to the func- 

 tions of sight, of smell and of hearing, and constitutes, perhaps, 

 one of the most remarkable phenomena that have been disclosed 

 by interrogating living nature. Flourens appears, however, to 

 have failed in proving that all the sensations demand for their 

 perception the integrity of the brain. He has himself stated 

 that an animal deprived of that organ, when violently struck, 

 " has the air of awakening from sleep," and that if pushed for- 

 wards, it continues to advance after the impelling force must 

 have been wholly expended. Cuvier has therefore concluded, 

 in his Report to the Academy of Sciences upon M. Flourens' 

 paper, that the cerebral lobes are the receptacle in which the 

 impressions made on the organs of sight and hearing only, be- 

 come perceptible by the animal, and that probably there too 

 all the sensations assume a distinct form, and leave durable im- 

 pressions, — that the lobes are, in short, the abode of memory. 

 The lobes, too, would seem to be the part in which those mo- 

 tions which flow from spontaneous acts of the mind have their 

 origin. But a power of effecting regular and combined move- 



1833. p 



