O B S E R V A T I O N S ON THE
1. Mufcles fupplied by the nerves imtatcd, often do not aft, but others
a dillance. Thus, when the outfide of tlie fore-arm is burnt, not the
:xtenfors, but the flexors of the fore-ai'm aft and remove it from the offending
caufe.
2. Mufcles moil connefted by their nerves do not fympathife moft.
3. Sympathy is not to be traced the reverfe way.
•4. Mufcles fupplied by intermediate nerves are at reif.
5. The fame nerve, irritated in different parts, produces different mo- *
tions.
6. The fame nerve, gently and violently irritated, produces different motions.
7. The fame nerve accuilomed to the ilimulus, aits lefs, or not at all
8. Antagonift mufcles receive nerves from the fame roots.
9. There are many fympathies where a connexion of nerves is not to be
traced.
10. Many impulfes affeftthc mind firft.
11. AfFedions of the mind, without the prefence of external objefts,
produce the fame effefts
Upon
• As the late ingenious Dr Wliytt, in 17C5, publiihed a Treatife on the Sympathy and Difeafes of
the Nerves, in which many of the above arguments againft the then common account of the caufe of
the
N E R V O U S S Y S T E M . lo i
Upon the whole, it appears, ijl, That the aftions above mentioned cannot
be accounted for on the yet known principles of mechanifm.
idly^ We obfei've, that the mufcular fibre varies its operation according
to the purpofe to be fcrved. That, for inftance, when a mufcular fibre is
punfturcd, it vibrates, which is the fitted-means of throwing off the offending
caufe; that the alimentary canal, acted on gently by the food, performs
a vei y complex periilaltic motion; that the abdominal mufcles aft
flowly and ileadily in expelling the contents of the reftum, but fuddcniy and
convulfively in vomiting; that tlie bladder of urine, from which there is a
fmall outlet, performs a flow and nniform contraftion in difcharging its
contents; whilft the heart contrafts witJi a jerk.
3f//y, The more we confider the various fpontaneous operations, the
more fully we iliall be convinced that they are the befl: calculated for the
prefervation and well-being of the animal.
Hence we are led to the conclufton, that they mull be direftcd and condufted
by a wife agent, intimately acquainted with the ilrufturc, and with
all the effefts it is capable of producing.
For the purpofes of phyfic, it may, perhaps, be fufllicient to know the
ilimuli which excite the fpontaneous motions; the manner in winch they
are perforined ; and to be convinced that w.e cannot account for them from
the known texture of the body, or from the yet known principles of mechanifm.
C c But
the fympathy of nerves arc mentioned, I think it neceflary to obferve, that I bad delivered all the above
arguments in niy eourfe of leisures,.eight years before Dr Whytt primed on that fubjeit, and three •
years before he wot e and delivered ledures upon it.
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