202 DIGESTION. [CHAP. xxiv. 



tinued sufficiently long, it is dissolved. The albumen is likewise 

 equally softened. The early changes which take place in a cubic 

 piece of solid white of egg, macerated in the digestive fluid, are 

 very characteristic. Its edges become of a pearly hue, semi-trans- 

 parent, almost fluid, breaking down under the slightest touch of 

 the finger; and, after longer digestion, the solid matters are com- 

 pletely dissolved. 



The solvent power of a digestive fluid made with the mucous 

 membrane of the stomach is strikingly displayed, if the results of 

 the digestion of meat and albumen with it be compared with those 

 obtained by digesting pieces of the same substances either with 

 simply acidulated water, muriatic, acetic, or phosphoric acids, 

 being used, or with an infusion of mucous membrane without 

 acid. Simple acidulated fluids produce little or no change in meat 

 and albumen in the course of twelve or twenty -four hours ; and 

 such change as is produced presents a marked contrast to that 

 caused by the infusion of mucous membrane with acid. No acid, 

 however, appears to cause more change than the phosphoric. 

 When the infusion of mucous membrane is used without acid, 

 rapid putrescence is produced. A similar effect results, although 

 with less intensity, from the use of too little acid; and, if alkali be 

 added, the putrefaction becomes still more rapid and intense. 



In these experiments, it is of great importance to pay close 

 attention to the temperature. It should be within the range of 

 from 90 to 110, the higher temperature increasing the energy of 

 the digestive action. If it reach the point at which albumen is 

 coagulated, all solvent change ceases, and the meat or albumen 

 becomes hardened. In a low temperature, likewise, there is no 

 change; the digestive fluid under such circumstances serving 

 merely to prevent decomposition. 



The antiseptic power of an acid infusion of gastric mucous mem- 

 brane is one of its most remarkable properties ; and in this respect 

 it resembles the gastric fluid itself, which, according to all observers, 

 is remarkably antiseptic, being capable of checking the further pro- 

 gress of putrefaction in meat in which that process had already 

 begun. This power seems principally due to the acid, the neutral- 

 ization of which destroys it ; and, if an infusion of mucous mem- 

 brane to which enough acid had not been added become putrescent, 

 its further decomposition may be checked by the addition of more 

 acid. We have kept the artificial digestive fluid for many months 

 in a bottle with a common cork, without its undergoing any 

 change. 



