Sect. II. i. 8. DEFINITIONS, 5 



a part of the perfpirable matter, and atmofpheric moiflure $ all 

 which, after having paiTed through thefe glands, and having 

 fufFered foine change in them, are carried forward into the 

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

 place its hourly waile. 



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

 ular motion, which carrier forwards their contents, after the 

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

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

 which becomes occasionally inverted or retrograde, as in vomit- 

 ing, and in the iliac paflion. 



II. 1. 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 mufcles ; but alfo 

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

 which reiides throughout the body, without being cognizable to 

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

 aily 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 fubjeel: to believe, that a fluid, perhaps much 

 more fubtiie than the electric aura, is feparated from the blood 

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

 we recollect, that the electric fluid itfeif is actually accumulated 

 and given out voluntarily by the torpedo and the gymnotus elec- 

 tric us, that an electric mock will frequently llimulate into mo- 

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

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

 the fingular figure of the brain and nervous fyitem feems well 

 adapted to diftribute it over every part of the body. 



For the medullary fubftance of the brain not only occupies 

 the cavities of the head and fpine, but palfes 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 {lender fibres, which conuVitute thofe mufcles 

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

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

 head s 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 cf the medullary fub fiance of 

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

 body, wrapped in its proper membrane. 



4. The 



