124 PHYSIOLOGY.. 



3. The brain then, is the organ of the intellectual and 

 moral faculties, the material instrument of the mind. \ This 

 is proved not only by comparative anatomy, and experiments 

 on animals, but by the history of injuries of the brain, com- 

 pared with those of other organs. We know that if the 

 nerves supplying any limb are severed, the will has no longer 

 any influence over it ; it is to all useful purposes a dead por. 

 tion of matter. The same is true of the spinal marrow. If 

 this be compressed by fracture or dislocation of the spine, 

 the whole body below that point, is deprived both of sensa- 

 tion and motion, but the mind loses none of its powers any 

 more than if a limb had been amputated. 



4. If the brain is not the seat of the intellectual facilities, 

 neither are any of the other organs of the body. *. The 

 lungs, the liver, the spleen, the intestines, or the kidneys, 

 may be affected with gangrene, and still the mind remains 

 clear ; though from sympathy, inflammation of any organ 

 may cause delirium, or other mental affections. Neither 

 is the heart the seat of the mind ; for cronic disease of that 

 organ, does not impair the mental faculties. Besides the 

 functions of all these organs are known and cannot be mis- 

 taken.* If the brain is not the seat of the intellectual facul- 

 ties, they cannot be said to have any seat in the body. 



5. But the effects of injuries of the brain are very diffe- 

 rent, for every cause which disturbs its action suddenly or 

 slowly, affects at the same time the mind. }j Inflammation of 

 the brain is always attended with delirium, or stupoij; pres- 

 sure on it, whether produced by depressed bone, foreign 

 bodies, a tumour, serum, blood or pus, always gives rise to 

 similar symptoms, and often destroy both sensation and 

 motion. In cases of apoplexy, where a person falls in a fit, 

 and becomes insensible, we find pressure on the brain from 

 effusion of blood or serum. In cases of lunatics, we find in 

 nearly all cronic cases, structural changes in the braird; but 

 if the case be recent, these changes though they probably 

 exist, yet may escape our imperfect means of investigation. 

 Alcohol, opium, and other narcotics affect the mind and the 



