SECT. II. i. *. DEFINITIONS. 5 



a part of the perfpirable matter, and atmofpheric moifture ; all 

 which after having patted through thefe glands, and having 

 fuffered fome change in them, are carried forward into the 

 blood, and fupply perpetual nourifhment to the fyftem, or re- 

 place its hourly wafte. 



8. The ftomach and inteftinal canal have a conflant vermic- 

 ular motion, which carries forward their contents, after the 

 lacteals have drank up the chyle from them ; and which is ex- 

 cited into adion by the ftimulus of the aliment we fwallow, but 

 which becomes occafionally inverted or retrograde, as in vomit- 

 ing, and in the iliac paflion. 



II. I. The word fenforium in the following pages is defign- 

 ed to exprefs not only the medullary part of the brain, fpinal 

 marrow, nerves, organs of fenfe and of the mulcles ; but alfo 

 at the fame time that living principle, or fpirit of animation, 

 which refides throughout the body, without being cognizable to 

 our fenfes, except by its effects. The changes which occafion- 

 ally take place in the fenforium, as during the exertions of voli- 

 tion, or the fenfations of pleafure or pain, are termed fenforial 

 motions. 



2. The fimilarity of the texture of the brain to that of the 

 pancreas, and fome other glands of the body, has induced the 

 inquirers into this fubjed to believe, that a fluid, perhaps much 

 more fubtile than the eledric aura, is feparated from the blood 

 by that organ for the purpofes of motion and fenfation. When 

 we recollc-d, that the eledric fluid itfelf is adually accumulated 

 and given out voluntarily by the ^orpedo and the gymnotus elec- 

 tricus, that an eledric (hock will frequently ftimulate into mo- 

 tion a paralytic limb, and laftly that it needs no perceptible tubes 

 to convey it, this opinion feems not without probability ; and 

 the fmgular figure of the brain and nervous fyftem feems well 

 adapted to diftribute it over every part of the body. 



For the medullary fubitance of the brain not only occupies 

 the cavities of the head and fpine, but paifes along the innumer- 

 able ramifications of the nerves to the various mufcles and or- 

 gans of fenfe. In thefe it lays afide its coverings, and is inter- 

 mixed with the flcnder fibres, which conftitute thofe mufcles 

 and organs of fenfe. Thus all thefe diitant ramifications of the 

 fenforium are united at one of their extremities, that is, in the 

 head and fpine \ and thus thefe central parts of the fenforium 

 conftitute a communication between all the organs of fenfe and 

 mufcles. 



3. A nerve is a continuation of the medullary fubftance of 

 the brain from the head or fpine towards the other parts of the 

 body, wrapped in its proper membrane. 



4. The 



