466 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 quantity 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 SiEBER 2 found 3.06 p. m. solids in the pure gastric juice of a dog. 

 NENCKI 3 found 5 milligrams sulphocyanic acid per 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 0; 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 

 almost 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. According to KLUG and WnoBLEWSKi 5 the pepsins found 

 in man and various higher animals are somewhat different, an observa- 

 tion which according to the experience of HAMMARSTEN is very prob- 

 able. 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 



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. 



6 Klug. Pfliiger's Arch. 60; Wr6blewski, Zeitschr. f. physiol. Chem., 21. 



