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.