432 DIGESTION. 



amylopsin, and diastase upon starch and glycogen is for the most part 

 maltose. This has been substantiated by BROWN and HERON. E. 

 KULZ and J. VOGEL 1 have also demonstrated that in the saccharifica- 

 tion of starch and glycogen, isomaltose, maltose, and some dextrose are 

 formed, the varying quantities depending upon the amount of ferment 

 and the length of its action. The formation of dextrose is claimed by 

 TEBB, ROHMANN, and HAMBURGER 2 to be only a product of the inver- 

 sion of the maltose by the maltase. 



The action of ptyalin in various reactions has been the subject of 

 numerous investigations. 3 Natural alkaline saliva is very active, but 

 it is not so active as when made neutral. It may be still more active 

 under certain circumstances in faintly acid reaction, and according to 

 CHITTENDEN and SMITH it acts better when enough hydrochloric acid is 

 added to saturate the proteins present than when only neutralized. When 

 the acid-combined protein exceeds a certain amount, then the diastatic 

 action is diminished. The addition of alkali to the saliva decreases its 

 diastatic action ; on neutralizing the alkali with acid or. carbon dioxide 

 the retarding or preventive action of the alkali is arrested. According 

 to SCHIERBECK, carbon dioxide has an accelerating action in neutral 

 liquids, while EBSTEIN claims that it has, as a rule, a retarding action. 

 Organic as well as inorganic acids, when added in sufficient quantity, 

 may stop the diastatic action entirely. The degree of acidity necessary 

 in this case is not always the same for a certain acid, but is dependent 

 upon the quantity of ferment. The same degree of acidity in the presence 

 of large amounts of ferment has a weaker action than in the presence of 

 smaller quantities. Hydrochloric acid is of special physiological interest 

 in this regard, for it prevents the formation of sugar even in very small 

 amounts (0.03 p. m.). Hydrochloric acid has not only the property 

 of preventing the formation of sugar, but, as shown by LANGLEY, NYLEN, 

 and others, may entirely destroy the enzyme. This is important in regard 

 to the physiological significance of the saliva. According to ROGER 

 and SIMON 4 ptyalin is not destroyed by gastric juice, but its action is 



1 Seegen, Centralbl. f. d. med. Wissensch., 1876, and Pfliiger's Arch., 19; Nasse, 

 ibid., 14; Musculus and v. Mering, Zeitschr. f. physiol. Chem., 2; Brown and Heron, 

 Liebig's Annal., 199 and 204; Kiilz and Vogel, Zeitschr. f. Biologic, 31. 



2 Tebb, Journ. of Physiol., 15; Rohmann, Ber. d. deutsch. chem. Gesellsch., 27; 

 Hamburger, Pfliiger's Arch., 60. 



3 See Hammarsten, Maly's Jahresber., 1; Chittenden and Griswold, Amer. Chem. 

 Journ., 3; Langley, Journal of Physiol., 3; Nylen, Maly's Jahresber., 12, 241; Chit- 

 tenden and Ely, Amer. Chem. Journ., 4; Langley and Eves, Journal of Physiol., 4; 

 Chittenden and Smith, Yale College Studies, 1, 1885, 1; Schlesinger, \irchow's Arch., 

 125; Schierbeck, Skand. Arch. f. Physiol., 3; Ebstein and C. Schulze, Virchow's Arch. 

 134; Kiibel, Pfliiger's Arch., 56. 



4 Compt. rend. soc. biol., 62. 



