The gastric juice, as already remarked, has no power over living animal matter,--a most wise and admirable provision, since otherwise it would at once have attacked and destroyed the very organ which produces it. This is the reason why certain worms are able to exist in the stomach of man and other animals; and if it were possible for an oyster swallowed directly from the shell to continue to live, it would also effectually resist every attempt at digestion. But it, in common with most other beings, soon perishes in circumstances so foreign to its habits; and when once dead, the gastric juice assumes the mastery, and speedily converts it into chyme. If any thing could have opened Montègre’s eyes to the fallacy under which he laboured in considering the gastric juice as almost identical with saliva, the circumstance we are now to mention would have sufficed. When a person, previously in good health, dies by a violent death, or when an animal is killed soon after a meal, it very often happens that, on opening the body after an interval of some hours, the stomach is found to be eroded, and its contents poured into the cavity of the abdomen, precisely as if a hole had been formed in it by ulceration. It was long before the reason of this was discovered; but at length it was ascertained to arise from _the action of gastric juice (the abundant secretion of which was provoked by the immediately preceding meal) upon the substance of the stomach, now subjected to its power from being deprived of life_. This fact has been so often verified, that it is by all admitted as incontrovertibly true.[27] If, therefore, the gastric juice be merely saliva and mucus, we might expect to find after death distinct traces of similar results from the contact of saliva within the mouth or gullet; but _there_ no such erosion is ever witnessed, nor, as Montègre himself admits, does saliva exert any solvent power whatever over dead animal matter out of the body. These facts appear quite sufficient to convince any unprejudiced mind. The power of _coagulating_ milk, and albumen or the white of eggs, is another remarkable property of the gastric juice,--and one so familiarly known, that in dairies an infusion of the stomach of the calf is in common use, under the name of runnet or rennet, for curdling milk. In infants, also, we know that the nurse’s milk has scarcely reached the stomach before coagulation takes place; a fact which leads many experienced mothers to infer that the infant is already suffering from acidity, and to counteract the supposed evils by repeated doses of magnesia--which, of course, do more harm than good. The coagulation of milk in the stomach, is so far from being a morbid process, that milk cannot be properly digested without it. By the separation and absorption of the fluid whey, the curd is reduced to a proper consistence for being acted upon, both by the gastric juice itself and by the contractions of the muscular coat.