PHYSIOLOGY OF THE NERVOUS SYSTEM. 



722P 



auditory nerve to justify our regarding either 

 of them as well calculated to perform this func- 

 tion. And, with respect to touch, the ganglia 

 on the posterior roots of the spinal and the 

 fifth nerves may perhaps be considered in the 

 same light; for this sense being diffused so 

 universally, in various degrees, over the whole 

 surface of the body, and being sealed in a great 

 number of different nerves, would need ganglia 

 in connection with all those nerves which are 

 adapted to the reception of tactile impressions. 

 The analogous sense of taste has its ganglia in 

 those of the glosso-pharyngeal and the fifth.* 



The upper and posterior part of the mesoce- 

 phale has already been referred to, as being 

 most probably that part of the brain which is 

 most directly influenced by emotional excite- 

 ment. Dr. Carpenter appears to localize the 

 seat of emotional influence more specially in 

 the corpora quadrigemina, and refers to certain 

 fibres, which he considers terminate in those 

 bodies, as channels of emotional impulses. 

 Although I am compelled to differ from this 

 able writer in this limitation of the centre of 

 emotion (so to speak), and am far from admit- 

 ting the existence of a distinct series of fibres 

 for emotional acts, I nevertheless think that the 

 arguments he advances are most applicable to 

 that view which refers the influence of emotion to 

 the grey matter of this entire region, which is 

 brought into connection with the spinal cord 

 by the fibres of the anterior pyramids, as well 

 as probably through the continuity of the olivary 

 columns and the posterior horns of the spinal 

 grey matter. 



Every one has experienced in his own person 

 how the emotions of the mind, whether excited 

 by a passing thought, or through the external 

 senses, may occasion not only involuntary 

 movements, but subjective sensations. The 

 thrill which is felt throughout the entire frame 

 when a feeling of horror or of joy is excited, or 

 the involuntary shudder which the idea of im- 

 minent danger or of some serious hazard gives 

 rise to, are phenomena of sensation and motion 

 excited by emotion. The nerves which take 

 their origin from the medulla oblongata, meso- 

 cephale, or crura cerebri, are especially apt to 

 be affected by emotions. The choking sensa- 

 tion which accompanies grief is entirely refer- 

 able to the pharyngeal branches of the glosso- 

 pharyngeal and vagi nerves, which come from 

 the olivary columns. The flow of tears which 

 the sudden occurrence of joy or sorrow is apt 

 to induce may be attributed to the influence of 

 the fifth nerve, which is also implanted in the 

 olivary columns, upon the lachrymal gland ; or 

 of the fourth nerve, which anastomoses with 

 the lachrymal branch of the fifth. The more 



* It may be urged against this conjecture respect- 

 ing the functions of the ganglia of the spinal nerves 

 and the fifth, that the analogy between these bodies 

 and the quadrigeminal tubercles is incomplete, in- 

 asmuch as the optic nerves are probably implanted 

 in the latter, but the nerves of touch merely pass 

 through the former. But, in truth, we know so 

 little of the positive relation of the nerves in ques- 

 tion to the ganglia, that no argument, either for or 

 against the above view, can rest upon suchjmper- 

 fect information. 



violent expressions of grief, sobbing, crying, 

 denote an excited state of the whole centre of 

 emotion, involving all the nerves which have 

 connection with it, the portio dura, the fifth, 

 the vagus, and glosso-pharyngeal ; and even 

 the respiratory nerves, which take their origin 

 from the spinal cord, as the phrenic, spinal 

 accessory, &c. And laughter, " holding both 

 his sides," causes an analogous excitation of 

 the same parts of the central organ and of the 

 same nerves. The very different effect pro- 

 duced by the excitement of the same parts 

 must be attributed to the different nature of 

 the menial stimulus. 



As the passing thought the change wrought 

 during the exercise of the intellect may excite 

 the centre of emotion, so this latter may exert 

 its influence upon the general tenor of the mind, 

 and give to all our thoughts the tinge of mirth 

 or sadness, of hope or despondency, as one or 

 the other may prevail. VVe say of one man, 

 that he is constitutionally morose ; of a second, 

 that he is naturally gay and mirthful; and of a 

 third, that he is a nervous man, and that he is 

 never likely to be otherwise. One man allows 

 his feelings to hurry him on to actions which 

 his intellect condemns ; whilst another has no 

 difficulty in keeping all his feelings in entire 

 subjection to his judgment. " Of two indivi- 

 duals with differently constituted minds," re- 

 marks Dr. Carpenter, " one shall judge of 

 everything through the medium of a gloomy 

 morose temper, which, like a darkened glass, 

 represents to his judgment the whole world in 

 league to injure him ; and all his determina- 

 tions, being based upon this erroneous view, 

 exhibit the indications of it in his actions, 

 which are themselves, nevertheless, of an en- 

 tirely voluntary character. On the other hand, 

 a person of a cheerful, benevolent disposition, 

 looks at the world around as through a Claude- 

 Lorraine glass, seeing everything in its brightest 

 and sunniest aspect, and, with intellectual fa- 

 culties precisely similar to those of the former 

 individual, he will come to opposite conclu- 

 sions : because the materials which form the 

 basis of his judgment are submitted to it in a 

 very different form."* Such examples abun- 

 dantly illustrate the important share which the 

 emotions take in the formation and develope- 

 ment of character, and how all things presented 

 to the mind through the senses may take their 

 hue from the prevailing state of the feelings. 

 If a certain part of the brain be associated with 

 emotion, it is plain that that part must be in 

 intimate connection with the seat of change in 

 the operations of the intellect, in order that 

 each may affect the other; that the former may 

 prompt the latter, or the latter excite or hold in 

 check the former. And this association of the 

 emotions with a certain portion of the brain 

 explains the influence of natural temperament, 

 and of varying states of the physical health, 

 upon the moral and intellectual condition of 

 individuals. We may gather from it how 

 necessary it is to a well-regulated mind that 

 we should attend not to mental culture only, 



* Carpenter's Physiology. 



