THE SEAT OF THE MENTAL FACULTIES. 615 Lesion of the cerebral hemispheres in animals gives rise to stupor and loss of memory; and in most lunatics considerable structural changes have taken place in the brain, although in other cases, particularly when the affection is inherited, the changes that have affected the microscopic fibrous texture cannot be recognised with our imperfect means of in¬ vestigation and defective knowledge. It has been said, as an objection to the brain being regarded as the seat of the mind, that very consider¬ able disease has been found affecting an entire hemisphere without the mental faculties having suffered: experiments on animals show, how¬ ever, that even sudden lesion of one hemisphere only does not imme¬ diately produce complete stupor; that this effect does not follow until both are removed; so that it would appear as if one hemisphere could aid the other, and even compensate for its inaction in the operations of the mind. Many distinguished writers, for example Bichat and Nasse, although they admit that the brain is the seat of the higher intellectual faculties, still maintain that other organs also, as the abdominal and thoracic viscera, have a certain connection with the mental functions, and incline to the belief that the source of the passions may possibly be in those organs. They formed their opinion partly on the circumstance of the viscera of the chest and abdomen being affected during the preva¬ lence of passions of the mind, and partly on their being frequently dis¬ eased in cases of insanity. The intestinal canal, liver, spleen, lungs, and heart are certainly frequently the seat of disease in lunatics, and occa¬ sionally even when no palpable change can be detected in the brain itself: and here the diseases of the abdominal or thoracic viscera may have been the exciting cause of the mental affection, but only in the same way as other causes might excite it by the impression communi¬ cated to the brain; there being in it some pre-existing disposition to morbid action, either hereditary or acquired. Hence in these patients, by removing the morbid change in the other viscera which have in¬ fluenced the brain, the disposition in the latter organ to abnormal action may be reduced again to a latent state. The relation in which the viscera stand to the mental emotions is, it must be confessed, still involved in much obscurity, (a) r! he passions, by means of the change which takes place in the brain, affect the whole nervous system. The exciting passions give rise to spasmodic actions of certain muscles, particularly those of which the nerves belong to the respiratory system (including the facial nerve); hence the crying, sigh¬ ing, sobbing, &c. with the spasmodic distortion of the features. In the depressing passions^ as apprehension and terror, all the muscles of the body lose their tone, the supply of motor influence from the brain and spinal cord being arrested; the feet are not able to bear the body, the features hang motionless and without expression, and the loss of power may be so great as to cause momentary paralysis of the whole body, particularly of the sphincters. The motions of the heart are affected by both the exciting and depressing passions. The sensations of many parts are altered. The secretions, as those of the lachrymal gland and (a) Positive knowledge and much suggestive matter on this subject will be found in Broussais’s Physiology. (See Translation, 3d edit.—By Drs. Bell and La Roche.)