1 88 PHYSIOLOGICAL CHEMISTRY 



maltose and this by the further action of an inverting enzyme (maltase) 

 is transformed into glucose. 



It is possible that the saliva as a digestive fluid is not absolutely 

 essential. The salivary amylase (ptyalin) is destroyed by the hydro- 

 chloric acid of the gastric juice and is therefore inactive when the chyme 

 reaches the intestine. Should undigested starch be present at this 

 point, however, it would be quickly transformed by the active pancreatic 

 amylase. This enzyme is not present in the pancreatic juice of infants 

 during the first few weeks of life, thus showing very clearly that a starchy 

 diet is not normal for this period. 



The pronounced influence of electrolytes upon the action of pancrea- 

 tic amylase and other amylases has been demonstrated many times. 1 

 In fact the removal of electrolytes from pancreatic juice by dialysis 

 yields a juice which possesses no power to split starch. It also appears 

 that the Cl or Br ion is absolutely essential to the activity of animal 

 amylases. 2 



It has been claimed that pancreatic amylase has a slight digestive 

 action upon unboiled starch. 



The extent to which amylase is present in the f eces has been taken as 

 the index of pancreatic activity. 



The third enzyme of the pancreatic juice is called pancreatic lipase 

 (steapsin) and is a fat-splitting enzyme. It has the power of splitting 

 the neutral fats of the food by hydrolysis, into fatty acid and glycerol. 

 A typical reaction would be as follows : 



Palmitin. Palmitic acid. Glycerol. 



Recent researches make it probable that fats undergo saponiftca- 

 tion to a certain extent prior to their absorption. The fatty acids 

 formed unite with the alkalis of the pancreatic juice and intestinal 

 secretion to form soluble soaps which are readily absorbed. It was 

 formerly believed that the fats could also be absorbed in emulsion 

 a condition promoted by the presence of the soluble soaps. After ab- 

 sorption the fatty acids are resynthesized to form neutral fats with 

 glycerol. 



Bloor 3 has reported experiments which "make it extremely probable 

 that fats can be absorbed only in water-soluble form and that saponi- 

 fication is a necessary preliminary to absorption." Petroleum hydro- 

 carbons and non-saponifiable esters, e.g., wool fat (lanolin) were un- 



1 For the literature see Kendall and Sherman: Jour. Am. Chem. Soc., 32, 1087, 1910. 



2 Wohlgemuth: Biochem. Zeit., 9, 10, 1908; and Kendall and Sherman: Jour. Am. Chem-. 

 Soc., 32, 1087 1910. Bierry: Biochem. Zeit., 40, 357, 1912. 



3 Bloor: Jour. Biol. Chem., 15, 105, 1913. 



