THE PRINCIPLE OF RECIPROCITY 393 



The resignation of systemic nervine control of functional 

 activity, which, again, characterises the onset of sleep, is 

 so imperceptible as to have absolutely baffled every 

 attempt of consciousness to appreciate it, the sway of 

 the sympathetic nervous system being substituted, for 

 that of the systemic, so silently, so to speak, and com- 

 pletely, as not to arrest the already slumbering attention. 



Moreover, the appreciation of the subjective feelings, 

 or " calls of nature," of hunger and thirst, by the 

 systemic nervous system, is of such constant and 

 unvarying occurrence, as to give rise to nothing more 

 than a routine feeling of attention, which is satisfied, or 

 answered, when all that is necessary to appease them has 

 been supplied to the oro-gastric organs. 



