Experiments on the Nervous System with Opium and Metalline Substances: Made Chiefly with the View of Determining the Nature and Effects of Animal ElectricityMonro, Alexander
Science
Experiments on the Nervous System with Opium and Metalline Substances: Made Chiefly with the View of Determining the Nature and Effects of Animal Electricity
Monro, Alexander
Electrophysiology -- Early works to 1800; Frogs -- Physiology; Nervous system -- Experiments -- Early works to 1800
COROLLARIES FROM THE ABOVE FACTS AND EXPERIMENTS.
FROM the above Facts and Experiments, it appears,
1. THAT the Frog, after its Head is cut off, feels pain, and, in
consequence of feeling, moves its Body and Limbs.
2. AS the Nerves of the hind Legs are not affected by Animal
Electricity, unless it be applied lower than the fifth Vertebra, these
Nerves do not seem to be derived solely or chiefly from the Brain or
Cerebellum.
3. AS Opium, after the Circulation ceases, affects Organs distant from
those to which it is applied, it is beyond doubt, that the latter
suffer in consequence of Sympathy of Nerves.
4. IT appears that, in this Animal, there is Sympathy of Nerves after
the Head is cut off; or that Sympathy of Nerves does not, in this
Animal, depend entirely on the connection of Nerves within the Head.
5. AS, after cutting off the Head, this Animal is susceptible of pain,
and, in consequence of that, performs voluntary motion, it appears
that, in it, the Brain is not the sole seat of the _Sensorium Commune_.
6. SEVERAL weeks after I had taken out the lowermost half of the Spinal
Marrow, and with it the Cauda Equina, I daily applied, for four days
running, Animal Electricity to the Sciatic Nerves, by passing a gold
Probe between them and the Os Sacrum, and excited several hundreds
of convulsions of the Thighs and Legs, and yet found that, on laying
bare the Femoral Nerves, and pinching them, the Muscles were slightly
convulsed.
HENCE, I apprehend, additional force is given to an opinion I ventured
many years ago to propose[3], that the Nerves do not receive their
energy wholly from the Head and Spinal Marrow, but that the texture of
every branch of a Nerve is such as to furnish it, or that the structure
of each Nerve is similar to that of the Brain.
7. FROM the above Experiments, it appears probable, in the highest
degree, that Opium may be absorbed in such quantity as to produce fatal
symptoms.
8. THE following circumstances concur in rendering inadmissible an
opinion lately proposed by M. FONTANA, that Poisons operate by changes
they produce on the mass of Blood, or on some unknown principle
connected with the Blood.
a. IF his opinion was just, Poison introduced into a Vein of the
extremities, so as to be in contact with this unknown principle, should
operate as quickly, and in the same manner as when the Poison is mixed
with the Blood near the Heart, which he admits is not the case[4].
b. CUTTING the Spinal Marrow in Frogs, before applying the Poison of
the Viper to their Legs, prevents it from killing them[5]; which should
not happen, if the Poison acted on the Blood alone.
c. HE acknowledges that an Animal bit in its Leg by a Viper,
instantaneously feels acute pain[6]; and it, in like manner, feels
instantly great uneasiness when the Poison is mixed with its Blood[7].
We know for certain, that, through the medium of the Nerves, we are
instantly rendered sensible of injury done to the most distant parts of
our Bodies.
Public-domain text, read in full here on John Shaqi.
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