GENERAL RECAPITULATION; PATHOLOGICAL APPLICATIONS. 831 



genitourinary organs is entirely derived from the Cerebro-Spinal system. 

 In no instance, however, can the Will exert any influence over the movements 

 of these parts; they are strongly affected by emotional states of mind; and 

 they frequently seem to respond to impressions made on remote organs. One 

 of the most remarkable cases of a definite motion uniformly excited through 

 the Sympathetic system is the dilatation of the pupil, which, after many im- 

 perfect attempts to determine its source, has now been shown by the experiments 

 of MM. Budge and Waller to be effected ^through the cervical portion of the 

 Sympathetic. For whilst irritation of the trunk of the cervical Sympathetic 

 by means of the magneto-electric machine produces dilatation of the pupil with 

 just as much certainty as irritation of the 3d pair determines its contraction, 

 section of that trunk occasions permanent contraction of the pupil, the action 

 of the 3d pair being no longer antagonized. But this, like the other motor 

 powers of the Sympathetic, is dependent upon the Spinal Cord ; for magneto- 

 electric irritation of any part of it between the first cervical and the sixth dorsal 

 vertebra produces the same effect, which is most decided when the irritation 

 is applied to the central part of this region. It appears from other experiments, 

 that the fibres by which this movement is effected pass through the Grasserian 

 ganglion, and are distributed to the eye by the ophthalmic branch of the 5th 

 Pair. 1 



848. If, then, the sensori-motor endowments of the Sympathetic trunks be 

 restricted to those fibres which are really Cerebro-Spinal in their origin or ter- 

 mination, it remains to inquire what are the functions of the true Sympathetic 

 fibres, whose vesicular centres lie in the ganglia of the Sympathetic System. 

 Upon this point we can only surmise ; but there appears strong ground for the 

 conclusion, that the office of these fibres is to produce a direct influence upon the 

 chemico-vital processes concerned in the Organic Functions of nutrition, secre- 

 tion, &c.; an influence which, although not essential to the performance of each 

 separate act, may yet be required to harmonize them all together, and to bring 

 them into connection with mental states. That the Nervous System does exert 

 such an agency will be hereafter shown (CHAP, xvin.) ; and reasons will there 

 be assigned for regarding the Sympathetic fibres as its principal, if not as its 

 sole channel. 



7. General Recapitulation, and Pathological Applications. 



849. In summing up the views which have been propounded in this Chapter, 

 with regard to the functions of the Nervous System, it will be advantageous to 

 follow the reverse order to that which has been previously adopted, and to pro- 

 ceed from above downwards, instead of from below upwards. 



I. The entire Nervous System, like other organs of the body, possesses vital 

 endowments peculiar to itself, in virtue of which it tends to respond in a deter- 

 minate manner to impressions made upon it ; its several parts being distin- 

 guished by the results of impressions acting upon each respectively. In so far, 

 then, as any part of the Nervous System merely reacts upon impressions which 

 are made upon it, we must regard its operations as automatic; and this as much 

 when they give rise to Psychical changes, as when they manifest themselves in 

 evoking Muscular movements, or in modifying the processes of Nutrition and 

 Secretion. 



ii. But the automatic actions of most parts of the Nervous System are sub- 

 ject, more or less completely, to the domination of the Will, a power which is 

 purely Psychical, and of which we know nothing but what we learn from our 

 own direct consciousness of its exercise. The power of the Will is the greatest 

 over the automatic actions of the highest portions of the Nervous Centres, which 



1 See " Gazette Medicale," 1851, Nos. 41, 44. 



