THE GASTRIC FLUID. 279 



Secretion and Properties of the Gastric Fluid. 



While the stomach contains no food, and is inactive, no 

 gastric fluid is secreted ; and inucus, which is either 

 neutral or slightly alkaline, covers its surface. But imme- 

 diately on the introduction of food or other foreign sub- 

 stance into the stomach, the mucous membrane, previously 

 quite pale, becomes slightly turgid and reddened with the 

 influx of a larger quantity of blood ; the gastric glands 

 commence secreting actively, and an acid fluid is poured 

 out in minute drops, which gradually run together and flow 

 down the walls of the stomach, or soak into the substances 

 introduced. The quantity of this fluid secreted daily has 

 been variously estimated ; but the average for a healthy 

 adult has been assumed to range from ten to twenty pints 

 in the twenty-four hours (Brinton). 



Xhe first accurate analysis of the gastric fluid was 

 made by Dr. Prout ; but it does not appear that it was 

 collected in any large quantity, or pure and separate 

 from food, until the time when Dr. Beaumont was 

 enabled, by a fortunate circumstance, to obtain it from 

 the stomach of a man named St. Martin, in whom there 

 existed, as the result of a gunshot wound, an opening 

 leading directly into the stomach, near the upper extremity 

 of the great curvature, and three inches from the cardiac 

 orifice. The external opening was situate two inches 

 below the left mamma, in a line drawn from that part 

 to the spine of the left ilium. The borders of the 

 opening into the stomach, which was of considerable size, 

 had united, in healing, with the margins of the external 

 wound ; but the cavity of the stomach was at last sepa- 

 rated from the exterior by a fold of mucous membrane, 

 which projected from the upper and back part of the 

 opening, and closed it like a valve, but could be pushed 

 back with the finger. The introduction of any mechanical 



