370 FUNCTIONS OF THE NERVOUS SYSTEM. 



on the Medulla Oblongata is shown on the same side. Many apparent ano- 

 malies present themselves, however, which are by no means easy of expla- 

 nation, in the present state of our knowledge. The disturbance of the Cere- 

 bral functions, occasioned by those changes in its nutrition which are com- 

 monly included under the general term of Inflammation, presents a marked 

 diversity of character, according to the part it affects. Thus it is well known 

 that the delirium of excitement is usually a symptom of inflammation of the 

 cortical substance or of the membranes of the hemispheres. This is exactly 

 what might be anticipated from the foregoing premises, since this condition 

 is a perversion of the ordinary mental operations, which are dependent upon 

 the instrumentality of the vesicular matter ; and it is evidently impossible for 

 the membranes to be affected with inflammation without the nutrition of this 

 substance being impaired, since it derives all its vessels directly from them. 

 On the other hand, inflammation of the fibrous portion of the Cerebrum is 

 usually attended rather with a state of torpor than with excitement ; and with 

 diminished power of the will over the muscles. It is stated by Foville, that 

 in acute cases of Insanity, he has usually found the cortical substance in- 

 tensely red, but without adhesion to the membranes ; whilst in chronic cases, 

 it is indurated and adherent : but where the Insanity has been complicated 

 with Paralysis, he has usually found the medullary portion indurated and 

 congested. 



487. The general result of such investigations is, that the Cerebrum is 

 the organ through which all those impressions are received which give rise to 

 the operations of the Intellect; and that it affords the power of occasioning 

 muscular contraction, in obedience to the influence of the Will, which is the 

 result of those operations. That all the operations of the Intellect are ori- 

 ginally dependent upon the reception of Sensations, is a position that can 

 scarcely be denied. If it were possible for a Human being to come into the 

 world, with a Brain perfectly prepared to be the instrument of mental opera- 

 tions, but with all the inlets to sensation closed, we have every reason to be- 

 lieve that the Mind would remain dormant, like a seed buried deep in the 

 earth. For the attentive study of cases, in which there is congenital defi- 

 ciency of one or more sensations, makes it evident that the Mind is uttterly 

 incapable of forming any definite ideas, in regard to those properties of ob- 

 jects, of which those sensations are particularly adapted to take cognizance. 

 Thus the man who is born blind can form no conception of colour ; nor the 

 congenitally-deaf, of musical tones. And in those lamentable cases, in which 

 the sense of touch is the only one through which ideas can be introduced, it 

 is evident that the mental operations would remain of the simplest and most 

 limited character, if the utmost attention be not given by a judicious instructor, 

 to the development of the intellectual faculties, and the cultivation of the 

 moral feelings, through the restricted class of ideas which there is a possi- 

 bility of exciting. The activity of the Mind, then, is just as much the result 

 of its consciousness of external impressions by which its faculties are called 

 into play, as the Life of the body is the consequence of the excitement of its 

 several vital properties by external stimuli. If these stimuli are prevented 

 from acting in the first instance, the state of inaction continues ; but when 

 once the mind has been aroused, the sensations which it receives are treasured 

 up by the Memory: and they may thus continue to be the sources of new 

 ideas, long after the complete closure of the inlets, by which new sensations 

 are ordinarily received. We have remarkable examples of this, in the vivid 

 conceptions which may be formed from the description of a landscape or a 

 picture, by those who have once enjoyed sight ; or in the composition of 

 music, even such as involves new combinations of sounds, by those who have 

 become deaf, as in the remarkable case of Beethoven. The mind thus 



