MUSCULAR INNERVATION 389 



those of voluntary origin and of purely neural phenomena, 

 save those of intellect and will, or cerebration proper ; its 

 enormous physiological importance thus can scarcely be 

 overestimated, and the necessity for its more exhaustive 

 study becomes more and more clamant. The histological 

 connections of the two nervous systems, the systemic and 

 the sympathetic, are well, if not completely, known, the 

 " rami communicantes" of the systemic penetrating into 

 every section of the sympathetic, and effecting a more or 

 less complete amalgamation of the two whether, however, 

 these " rami communicantes " contain motor and sensory 

 elements in equal or varying proportions, has not yet 

 been determined. We are, therefore, at liberty to infer that 

 both elements enter and leave the histological combination 

 in physiologically balanced ratio, and that the exchange of 

 systemic and sympathetic nerve energy respectively is 

 maintained, in virtue of this histological arrangement, at 

 neutral and non-explosive rate. The normal working of 

 the combination is characterised by an almost complete 

 absence of consciousness, on the part of the cerebro-spinal 

 centres, of the various steps and stages of that work, the 

 whole being effected without " let or hindrance," or 

 apparent friction, amongst the agents supervising it, the 

 sympathetic neuro-musculature being alone sufficient to 

 meet all emergencies. When, however, any element of 

 discord or friction enters into the working of these dual 

 elements, a consciousness of its presence is at once the 

 result, through the sensory fibres of the " rami communi- 

 cantes" which consciousness so rouses the vis medicatrix 

 nature, that she, if it be slight and easily removable, 

 adopts the requisite means for its removal, or, if not, 

 " calls aloud " to the " sleeping partner " for assistance, 

 through intensification of the sensory disturbance and 

 unmistakable pains. 



