METHODS OF OBTAINING GASTRIC JUICE. 



If the gastric juice be completely discharged externally through a gastric 

 fistula, the alkalinity of the intestine is so strong, that the urine becomes alkaline 

 (Maly). 



The acid gastric juice of the iiew-born child is already fairly active; casein is 

 most easily digested by it, then fibrin and the other proteids (Zweifel). When 

 the amount of acid is too great in the stomach of sucklings, large firm indigestible 

 masses of casein are apt to be formed (Simon, Biedert see Milk). This occurs 

 more especially after the use of cow's milk. 



165. Methods of obtaining Gastric Juice. 



Historical. Spallanzani caused starving animals to swallow small pieces of 

 sponge, enclosed in perforated lead capsules, and after a time, when the sponges 

 had become saturated with gastric juice, he removed them from the stomach. To 

 avoid the admixture with saliva, the sponges are best introduced through an 

 opening in the oesophagus (Manassei'n). Starving animals were forced to swallow 

 small stones, which excited the secretion of gastric juice. After a time, the 

 animals were killed, and the juice collected. 



Dr. Beaumont (1825), au American physician, was the first to obtain human 

 gastric juice, from a Canadian named Alexis St. Martin, who was injured by a 

 gunshot wound, whereby a permanent gastric fistiila was established. Various 

 substances were introduced through the external opening, which was partially 

 covered with a fold of skin, and the time required for their solution was noted. 

 Bassow (1842,) Blondlot (1843), and Bardeleben (1849) were thereby led to make 

 artificial gastric fistulas. 



Gastric Fistula. The anterior abdominal wall is opened by a medium incision 

 just below the ensiform cartilage, the stomach is exposed, and its anterior wall 

 opened and afterwards stitched to the margins of the abdominal walls. A strong 

 cannula is placed in the fistula thus formed. A silver cannula about an inch wide, 

 and with a flange, is introduced into the stomach, so that the flange lies in contact 

 with the gastric mucous membrane. The inner surface of the tube of the cauuula 

 is provided with a screw into which a similar cannula is screwed, and its flange 

 comes in contact with the abdominal wall. When the two are placed together 

 they have the form of J*, where a passes into b. [When the two parts of the 

 cannula are screwed together, the flanges keep the abdominal walls and gastric 

 walls in contact, until they become united organically.] As a rule, the tube is 

 kept corked. If the ducts of the salivary glands be tied, a perfectly uncompli- 

 cated object for investigation is obtained. 



According to Leube, dilute human gastric juice may be obtained by means of a 

 syphon-like tube introduced into the stomach. Water is introduced first, and 

 after a time it is withdrawn. 



Artificial Gastric Juice. An important advance was made when Eberle 

 (1834) prepared "artificial gastric j nice," by extracting the pepsin from the gastric- 

 mucous membrane with dilute hydrochloric acid. A certain degree of concentra- 

 tion, however, is required (Schwann). Four litres of a watery solution of 

 O'S-1'0-1'7 of pure hydrochloric acid per 1000 (Briicke) are sufficient to extract 

 the chopped-up mucous membrane of the pig's stomach. Half a litre is infused 

 with the stomach and renewed every six hours. The collected fluid is afterwards 

 filtered (Hoppe-Seyler.) The substance to be digested is placed in this fluid, and 

 the whole is kept at the temperature of the body, but it is necessary to add a little 

 HC1 from time to time (Schwann). The HC1 may be replaced by ten times its 

 volume of lactic acid (Lehmann) and also by nitric acid ; while oxalic, sulphuric, 

 phosphoric, acetic, formic, succinic, tartaric, and citric acid are much less active ; 

 butyric and salicylic acids are inactive. 



