164 PHYSIOLOGICAL CHEMISTRY 



an average total acidity of 30 and an average free acidity of 18.5. 

 The residuum is often colored by bile. This is particularly true if 

 the fluid has a relatively high acidity. Trypsin is also generally present. 

 These findings indicate regurgitation (see page 171). Pathological 

 residuums may contain blood, pus, mucus and may show food retention 

 which is indicative of disturbed food evacuation. The quantity 

 may also be much increased due to hypersecretion. A residuum of 

 large volume possessing a total acidity value of 70 or over may indicate 

 ulcer. 



Analysis of Residuum. Remove the residuum as directed under (5), below, 

 and analyze the fluid according to methods outlined on page 165. 



3. The Test Meal. Before making an analysis of the stomach 

 contents it is customary to introduce something into the stomach which 

 will stimulate the gastric cells. The response to this stimulation is 

 then measured clinically by the determination of total acidity, free 

 acidity and pepsin in the stomach contents. Many forms of test meal 

 have been used. 



The test meal most widely employed is the Ewald test meal. This consists 

 of 2 pieces (35 grams) of toast and 8 ounces (250 c.c.) of tea. 



Inasmuch as it was demonstrated in the author's laboratory 1 that 

 water gave a similar gastric stimulation to that produced by the Ewald 

 meal it was suggested that a simple water meal might be substituted 

 for the Ewald meal. This water meal also has the added advantage 

 of enabling one to determine the presence of food rests and to test more 

 accurately for lactic acid, blood and bile. 



4. The Retention Meal. In order to obtain more information 

 regarding gastric motility than is furnished by the ordinary test meal 

 described above the patient may be fed a so-called retention meal. This 

 meal is fed in place of the regular evening meal and contains substances 

 readily detected. In the morning before breakfast (7-8 a. m.) remove 

 the stomach contents (residuum, see page 163) by aspiration and examine 

 for food rests. The normal stomach should give no evidences of food 

 retention. A satisfactory retention meal consists of 4 ounces each of 

 boiled string beans and rice. 2 Diets containing prunes, raspberry mar- 

 malade, lyeopodium powder, etc., have also been employed. In many 

 instances an ordinary mixed diet will serve the purpose. 



5. Removal of Samples for Analysis.- At intervals of exactly 15 

 minutes from the time the test meal is eaten until the stomach is empty 



^ergeim, Rehfuss, and Hawk: Jour. Biol. Chem., 19, 345, 1914. 



Rehfuss, Bergeim and Hawk: Jour. Am. Med. Ass'n, 63, n, 1914. 

 8 Myers and Fine: Essentials of Pathological Chemistry, 1913. 



