The menstruum is supposed to _act_ by "chymical attraction," from
having "chymical affinity" on the involved "chymical solid," which
enables it to draw out the elementary atoms of the solid: whereas the
_inert_ menstruum does nothing; it is but an interstitial recipient for
the atoms to be forced into, as they become centrifugally forced out
of the solid. And because the atoms of a body are of different sizes,
some make novel interstices, and thus expedite the dissolution. Only by
increasing the number and kind of interstices, can diluting a menstruum
with water increase what is imagined to be its solvency. Neither
chymical properties, nor chymical strength of a fluid, if it had any
such, could be increased by dilution, and the stronger should dissolve
that which the weaker is said to dissolve. The contrary supposes that
the force which breaks a stone is too strong to break a nutshell.
Mechanical dissolution by the centrifugal pressure is independent of
_chymicalities_.
_Gastric solution_ is effected similarly: the juice has none of the
chymical properties of Liebig, nor does ingestion stand in need of the
living principle of Coombe; the former are imaginary, the latter is
denied from gastric solution taking place in a tea-cup. The gastric
juice is an interstitial receiver of the elements of the pulp, when
forced out by the centrifugal pressure into the gastric menstruum,
as those of soap into water. The pulp and its _striæ_ are disunited,
mechanically decomposed, not abraded: some of its elements escape
into the air within the stomach, which, by disturbing the equilibrium
within, promote irregularity of pressure on the outside of the sac,
which causes the _pliæ_ to be in the peristaltic motion, supposed to be
caused by the stomach stimulating itself. The same circumstances take
place within and without the intestines. The whole process of digestion
is dynamic, in which the only stimulant is pressure.
Of the various conjectures on the origin of the gastric juice, there
cannot be any more unreasonable than that which considers it a fluid
_sui generis_, and as having origin out of the stomach. All fluids are
compounds; and those belonging to the body may be said to be formed
out of, or by commixture with others. To suppose for an instant, that
a fluid, which is _destructive of all flesh_, should have existence
out of the stomach, and remain harmless in some _fleshy_ vessel as
long as the stomach is empty of food, or until food is required to
"stimulate" its flow from without through the _papillæ_ of the villous
lining into the stomach, is a most strange physiologic oversight. Why
not rather conclude at once, that the flesh-destroying juice exists
only where it is required and for immediate service, and where only
there are preventive means, the peristaltic motion, against it proving
injurious to the flesh of the stomach; and to the vessels of secretion
it would be injurious, hence, not as the juice but chyme it is passed
out of the stomach into the system. Under such circumstances, the
suggestion is nothing unreasonable, that, _there is no gastric juice
out of the stomach, nor within, but while there is food present to
contribute one or more of its elements to the other juices, including
the saliva, towards effecting its completion as a fit interstitial
gastric menstruum, for receiving the elementary constituents of the
pulp under mechanical decomposition by the centripetally disuniting
pressure of the medium of space_. Like the all de-electrising medium
of fire, which exists only where and while it is being formed, the
gastric juice should be looked upon as if _designed to be of difficult
formation_; made more so by depending on the food for its completion,
which is not a matter of "observation" within the stomach, or in the
tea-cup: neither is the perfect juice, which may be sponged or syringed
from the bottom of the stomach, any proof that as such precisely it
came from the _papillæ_, as some suppose. As to the papillary flow
being _stimulated_ by the food, with as bad philosophy it might be
said, charmed; or that clockwork is _stimulated_ by the weights. The
flow is promoted by the pulp, as were the latter a piece of sponge. And
that the papillary flow is but a constituent, not the flesh-destroying
juice, in promoting ingestion, is evident from the hunger pain it
promotes while harmlessly accumulating out of the stomach, indicating
the stomach being empty; and the relief experienced at its source when
discharged into the stomach, it is, which has given rise to the idea,
that certain organs _sympathise_ with the stomach.
Such metaphorical expressions may pass for the poetry of pathology, but
hitherto have stood in the way of deep research. Ingestion is expedited
by sleep, in consequence of the accumulation of minus-pressure matter
in the gastric region and stomach at the time; and sleep is promoted
by imperfect mastication causing a deficiency of saliva in the stomach
which is compensated by minus-pressure matter of the thus provoked
comatose flow. The pollparrot masticates but little, if at all, and
sleeps regularly after breakfast.