SET. II. DEFINITIONS* 7 



SECT. II. i. 



EXPLANATIONS AND DEFINITIONS. 



I. Outline of the animal economy . II. i. Ofthejerifo- 



rium. 2. Of the brain and nervous medulla. 3. 



A nerve. 4. A mufcular fibre. 5. The immediate 



organs of fenfe. 6. "The external organs of ' fenfe. 7. 



An idea or fenfual motion. 8. Perception. 9. Sen- 



fation. 10 Re collection and fuggeft ion. n. Habit, 



caufation> affbciation, catenation. 12. Reflex ideas. 



13. Stimulus defined. 



As fome explanations and definitions will be neceffary in the profecu- 

 tion of the work, the reader is troubled with them in this place, 

 and is intreated to keep them in his mind as he proceeds, and to 

 take them for granted, till an apt opportunity occurs to evince their 

 truth ; to which I /hall premife a very fhort outline of the animal 

 economy. 



I. i. THE nervous fyftem has its origin from 

 the brain, and is diflributed to every part of the 

 body. Thofe nerves, which ferve the fenfes, prin- 

 cipally arife from that part of the brain, which is 

 lodged in the head ; and thofe, which ferve the 

 purpofes of mufcular motion, principally arife from 

 that part of the brain, which is lodged in the neck 

 and back, and which is erroneoufly called the fpi- 

 nal marrow. The ultimate fibrils of thefe nerves 

 terminate in the immediate organs of fenfe and 

 mufcular fibres, and if a ligature be put on any part 

 of their paflage from the head or fpine, all motion 

 and perception ceafe in the parts beneath the liga- 

 ture. 



a. The 



