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.
