X. 
Thefe nervous Tubes contain a Fluid *, whofe 
Nature and Property is not fo much to nourifli as to 
inflate 5 
* This Opinion leads me to the following Queries : 
1. Is it not well known, that confined Air is capable, by a proper 
Impulfe, of performing more violent and fwift Motions, than any 
Succus or 'Liquor that can be conceiv’d ? 
2- Are not animal Spirits a Quid occultum ? 
3. Is not the Blood the foie Mafs from which every Liquor of 
the Body is fecreted ? If fo, may we not as rationally fuppofe, that 
any exalted or refined Liquors, for whatfoever Purpofes defign’d, 
may be fent off through exquifitely minute Canals, to anfwer their 
feveral Ends, immediately from the Mafs, as to imagine fuch are only 
fecreted in the Brain? For', by the Affiftance of the folar Microfcope, 
fuch exquifitely minute Canals, as could not be difcerned even by 
the double Microfcope in a full View of the Circulation in the 
Mefentery of a Frog, appear’d to be fill’d with a clear Liquor paffing 
rapidly from the Veffels wherein I faw the Blood circulate, and 
which feemed to me fome Hundreds of times fmallerthan thole Vef- 
fels from which they fprung. 
4. Is not the Blood full of Air, and is it not daily fupply’d by 
Infpiration in the Lungs ? If fo, why may we not as well fuppofe, 
that the Blood carries to the Brain, and there depofites, a fufficient 
Quantity of an Aura, to fupply the Nerves and mufcular Cells, in 
order to their Motion, as we fhall explain it by-and-by, as that ani- 
mal Spirits are fecreted there? any Liquor, as we have faid before, 
being lefs likely to ferve to fwift Motions than Air. 
Now till the Negative to thefe Queries can be proved, I cannot 
help thinking, that nothing but this inflating Aura can enter into 
the Cavities of the mufcular Cells ; and confequently mu ft confider 
the Brain as deftined only for treafuring up this inflating Aura , and 
the nervous Fibres as Pipes to convey k to the mufcular Fibres, into 
whofe Cells they alone can open ; that no Nutrition can proceed 
any other Way than, immediately from the Blood-veffels to the Parts 
that require it ,• and that therefore it may, with fome Probability, 
be concluded, that the Encephalon and fpinal Marrow , Nerves , and 
mufcular Fibres , are a Set of mechanical Organs, exempt from any 
other Office, than to caufe Morion and Senfation by Inflation only, 
fo that every Mufcle that moves may juftly be Laid to be blown up 
into Motion. 
