442 DIGESTION. 



refer only to impure gastric juice they are of little value. RosEMANN, 1 

 who has investigated the gastric juice secreted by a dog after sham 

 feeding found an average of 4.22 p. m. solids, among which 1.32 p. m. 

 were mineral bodies and about 2.90 p. m. organic substance. The amount 

 of nitrogen in one case was 0.36 p. m., in another 0.54 p. m. and the quan- 

 tity of HC1 was about 5.6 p. m. The ash consisted chiefly of potassium 

 chloride, namely 980-990 p. m. of the inorganic part. NENCKI and 

 SiEBEB 2 found 3.06 p. m. solids in the pure gastric juice of a dog. NENCKI 3 

 found 5 milligrams sulphocyanic acid in a liter of gastric juice of a dog. 



In the ash of human gastric juice after sham-feeding ALBu 4 found 

 356.2 p. m. K 2 O; 226.5 p. m. Na 2 O, and 497.3 p. m. Cl. The amount 

 of salts insoluble in water was 23.9 p. m. In hyperacidity he found 

 nearly the same composition. 



Besides the free hydrochloric acid, pepsin, rennin, and a lipase are 

 the other physiologically important constituents of gastric juice. 



Pepsin. This enzyme is found, with the exception of certain fishes, 

 in all vertebrates thus far investigated. 



Pepsin occurs in adults and in new-born infants. This condition 

 is different in new-born animals. While in a few herbivora, such as the 

 rabbit, pepsin occurs in the mucous coat before birth, this enzyme is 

 entirely absent at the birth of those carnivora which have thus far been 

 examined, such as the dog and cat. 



In various invertebrates enzymes have also been found which have a 

 proteolytic action in acid solutions. It has been shown that these enzymes, 

 nevertheless, are not in all animals identical with ordinary pepsin. Accord- 

 ing to KLUG and WROBLEWSKI 5 the pepsins found in man and various 

 higher animals are somewhat different, an observation which accord- 

 ing to the experience of HAMMARSTEN is very probable. Enzymes also 

 occur in various plants and animal organs, although not identical with 

 pepsin, but which act in acid reaction. The enzyme obtained from the 

 Nepenthes, which dissolves proteins only in acid reaction, stands very 

 close to pepsin. An enzyme more closely related to trypsin or erepsin 

 (see sections III and IV) is, on the contrary, GLAESSNER'S pseudopepsin, 

 which according to him is the only peptic enzyme in the pyloric end. 

 Pseudopepsin, whose existence is disputed by KLUG, while others (REACH, 

 PEKELHARING) affirm its occurrence in the mucous membrane, cannot, 

 according to HAMMARSTEN, either be the only or the most prominent 

 peptic enzyme of the pyloric part. According to GLAESSNER, it also 



1 Pfliiger's Arch., 118. 



2 Zeitschr. f. physiol. Chem., 32. 



3 Ber. d. d. Chem. Gesellsch., 28. 



4 Zeitschr. f. Path. u. Therap., 5. 



5 Klug, Pfluger's Arch, 60; Wroblewski, Zeitschr. f. physiol. Chem., 21. 



