130 BIOLOGICAL CHEMISTRY 



The relative amounts of the various enzymes in the pan- 

 creatic juice have been stated to be adapted to the different 

 kinds of foods,* but this statement has been contradicted. 



TABLE XXVI 



Composition of Pancreatic Juice obtained by the injection of 



Secreting 



Alkalinity, 10 cc.= 12-700 n NaOH 



Total solids 1-6% 



Total protein 0-5% 



Ash 1-0% 



Chlorides 0-28% 



During secretion changes take place in the granules like 

 those described in connection with the salivary glands. J] 



Digestion in the Small Intestine 



The final stages of digestion are brought about by enzymes 

 which seem to be associated with the cells lining the small 

 intestine. The carbohydrates have been so altered that the 

 polysaccharides have been mostly converted into maltose ; 

 some of the maltose has been converted into glucose. Cane- 

 sugar may have been partially hydrolysed by the acid of the 

 gastric juice and lactose is unaltered. The enzymes of the 

 small intestine complete the hydrolysis of the carbohydrates 

 to monosaccharides. Maltose is acted on by maltase, lactose 

 by lactase and cane-sugar by invertase, producing respectively 

 two molecules of glucose, one molecule of glucose and one of 

 galactose, and one molecule of glucose and one of fructose. 

 Thus the carbohydrates are converted into the simplest, most 

 soluble and most easily diffusible products. 



The presence of amylases as mentioned previously can be 

 shown by the production from starch of some substance 

 capable of reducing alkaline copper solution. Invertase can 

 likewise be shown by the production from cane-sugar of some 

 substance capable of reducing alkaline copper solution. 

 Maltose and lactose are reducing sugars, so in order to show the 

 presence of maltase and lactase we must either make a careful 

 quantitative estimation of the reducing power of the solution 

 before and after incubation with the supposed enzyme, or 



* A. A. Walter, Arch, des Sc. biolog., 1899, vol. 7, p. i. 

 f L. A. E. de Zilwa, Journ. PhysioL, 1904, vol. 31, p. 230. 



