*J2 CATENATION OF MOTIONS. SECT. XVII. 3. 



motions, their catenations are indiflbluble but by 

 the deftru&ion of the animal. 



3. Where a new link has been introduced into a 

 circle of a&ions by fome accidental defect of ftimu- 

 lus ; if that, defect of flimulus be repeated at the fame 

 part of the circle a fecond or a third time, the defec- 

 tive motions thus produced, both by the repeated 

 jdefecl: of flimulus and by their catenation with the 

 parts of the circle of actions, will be performed with 

 lefs and lefs energy. Thus if any perfon is expofed 

 to cold at a certain hour to day, fo long as to render 

 fome part of the fyftem for a time torpid ; and is 

 again expofed to it at the fame hour to-morrow, and 

 the next day ; he will be more and more affecled by 

 it, till at length a cold fit of fever is completely form- 

 ed, as happens at the beginning of many of thofe 

 fevers, which are called nervous or low fevers. 

 Where the patient has flight periodical (hiverings 

 and palenefs for many days before the febrile pa- 

 roxyfm is completely formed* 



4. On the contrary, if the expofure to cold be for 

 To fhort a time, as not to induce any confiderable 

 cFegree of torpor or rjuiefcepce, and is repeated 

 daily as above mentioned, it lofes its effect more 

 and more at every repetition, till the conftitution 

 can bear it without inconvenience, or indeed with- 

 out being confcious of it. As in walking into the 

 cold air in frofty weather. The fame rule is appli- 

 cable to increafed ftimulus,'as of heat, or of vinous 

 fpirit, within certain limits, as is applied in the two 

 laft paragraphs to Deficient Stimulus, as is further 

 explained in Sed. XXXVI. on the Periods of DifV 

 cafes. 



5. Where irritation coincides with fenfation to 

 produce the fame catenations of motion, as in inflam- 

 matory fevers, they are excited with (till greater 

 energy than by the irritation alone. So When chiU 

 dren expeft to be tickled in play, by a feather light- 

 ly paffed over the lips, or by gently vellicating the 



foles 



