DIGESTION

The general proce by which food is converted into chyme in the stomachs of animals, and bv which it is rendered fit for the production of chyle, and ultimately of blood. The term digestion is also more generally applied to the entire functions of the intestinal canal. The phenomena of digestion, though exclusively chemical, are also under the immediate influence of vitality, and are consequently perfectly different from any changes which the food suffers out of the body; hence the unsatisfactory conclusions of the older physiologists, who considered attrition, fermentation, and similar mechanical and chemical proce es as sufficient to account for the extraordinary changes that are produced. It has been clearly ascertained that the influence of the nervous system is e ential to the due performance of the functions of the stomach; and that when the brain, cr the nerves that supply that viscus, are either injured or divided, digestion is either impaired or altogether suspended, and the food then ferments and putrefies instead of digesting. It haa been said that the transmi ion of a current of electricity through the nerves is equivalent to their connection with the brain, and that under such circumstances the stomach, notwithstanding the division of its nerves, continues its functions; but these, and other statements in which electricity is said to be equivalent to the nervous and cerebral agency, require much more extended experimental proofs than they have hitherto received, before they can be admitted as true interpretations. Digestion. In Surgery, this term was formerly applied to the treatment by which wounds or ulcers were brought Into that state In which they form healthy pus: the remedies or applications promoting this object wero termed digestives. [s. 361]