CHAP. XXIV.] CHANGES IN THE GASTRIC MUCOUS MEMBRANE. 197 



white colour and a wrinkled appearance, from the existence of 

 numerous minute folds upon it, which stretching does not obli- 

 terate. At the same time, the whole surface of the membrane is 

 covered by a layer of mucus, which varies in its thickness and in 

 its viscidity. 



It may be inferred from Beaumont's observations, that similar 

 phenomena are met with in the human stomach. Beaumont found, 

 that, immediately on the introduction of food into the stomach, the 

 vessels of the mucous membrane became more injected, much, no 

 doubt, as those of the conjunctiva of the eye would become filled 

 on the application of a foreign body ; and that its colour became 

 deeper, being changed from a pale pink to a deep red. A pure, 

 colourless, and slightly viscid fluid, with distinct acid reaction, was 

 then observed to distil from the surface of the membrane, and to 

 collect in drops at various points of it, trickling down the wall of 

 the stomach until it mingled with the food. The exudation of this 

 fluid was always excited by the contact with any foreign substance ; 

 even so smooth a surface as the bulb of a thermometer invariably 

 excited on its introduction, and even when it had been previously 

 ascertained that the stomach was empty, and exhibited no reaction. 



During fasting, Mr. Beaumont observed no evidence of the exist- 

 ence of such a fluid as this, the sole contents of the stomach being 

 then only a little viscid mucus, occasionally slightly acidulated. 

 Beaumont describes this fluid as being clear, transparent, inodorous, 

 saltish, and resembling in taste thin mucilaginous water slightly 

 acidulated with muriatic acid. It is, he states, readily diffusible in 

 water, wine, or spirits, and effervesces slightly with alkaline car- 

 bonates. It coagulates albumen, and is powerfully antiseptic, 

 checking putrefaction in meat. When pure, it will keep for many 

 months ; but if diluted with saliva, it becomes foetid in a few days. 

 According to the analysis of Professor Dunglison it contained free 

 muriatic and acetic acids, phosphates and muriates of potass, soda, 

 magnesia, and lime. 



Beaumont's observations were made during a period extending 

 between May, 1825, and March, 1833. Various observations and 

 experiments, commencing from a date long antecedent to this, had 

 led to a very generally received opinion among physiologists, that 

 the mucous membrane of the stomach was the seat of a special se- 

 cretion, which had a great share in effecting the changes which the 

 food undergoes in the stomach. 



Reaumur was the first to offer satisfactory proof of the secretion 

 of a solvent fluid for the purposes of digestion by the walls of the 



