THE PRINCIPLE OF RECIPROCITY 391 



of such a complex organism as the human body, it is 

 impossible to overestimate, inasmuch as at every patho- 

 logical " turn of events " we are brought face to face with 

 a violation of that treaty, and cannot see the restoration 

 of physiological order, until we and the vis medicatrix 

 nature have succeeded in restoring the status quo ante. 



To illustrate the truth of these remarks, let us take one 

 conspicuous example, which may be accepted as typical, 

 viz. the great function of nutrition. In this the systemic 

 nervous system, by virtue of its possession of the senses 

 of taste, smell, sight, and touch, etc., and the faculty of 

 reason, determines what is best for the nutrition of the 

 body which it innervates, and supplies the requisite not 

 unfortunately without mistakes materials, to the waiting 

 and ready sympathetically innervated musculature of the 

 post-pharynx, which at once, and without option, trans- 

 mits them to the all but entire control of its associated 

 sympathetically innervated, digestive, assimilative, and 

 eliminatory textures and organs, for distributive disposal 

 and final elimination. If this can be accomplished without 

 " let or hindrance," the systemic system is rewarded for 

 its implicit trust in its co-treaty power, and co-partner by 

 the nutritive and eliminatory work involved being done 

 to its entire satisfaction and abiding comfort ; if, however, 

 as is always possible in the best-regulated labour compacts, 

 elements of friction and disturbance have been unfortun- 

 ately allowed to enter, a period of discomfort and mutual 

 distrust and recrimination between the two systems ensues, 

 until the vis medicatrix succeeds in clearing the total dual 

 commonwealth of every cause of discomposure, and in 

 restoring its lost physiological order. It is nothing less 

 than astonishing to observe with what long-suffering, and 

 infinite disposition to meet its obligations, the sympathetic 

 system labours, and with what success it accomplishes its 

 unaided, and often thwarted, labours, when called upon to 

 prepare from the most unpromising and heterogeneous 

 materials the plasmic elements of nutrition, and to dis- 

 tribute them unerringly to the expectant tissues and 

 organs of the body. It is, moreover, not less astonishing 

 to observe with what precision and executionary ability 

 it seizes, in exchange for its new tissue elements, the 



