I 86 PHYSIOLOGICAL CHEMISTRY. 



high temperature destroys the activity of the enzyme, as in the case of 

 saliva. Note in the solution of the starch the dextrin stages which may 

 be followed by the iodine test. For the complete conversion of the 

 amount of starch here taken some hours may be required. This depends 

 on the strength of the pancreas extract. 



It is well to vary the experiment by employing some fresh minced gland 

 in place of the extract. The pancreas powder may also be used. 



We have then the two principal reactions here, the forma- 

 tion of malt sugar and the inversion of the same. It is not 

 possible to isolate the enzyme which produces the one reaction 

 from that which gives rise to the other, but that both are prod- 

 ucts of the cells of the pancreas has been satisfactorily shown 

 against the view that the inverting enzyme is furnished by the 

 so-called intestinal juice. It may be recalled that both reac- 

 tions are hydrolytic. 



It is likely that the living gland does not contain the active 

 ferment itself but a preferment or zymogen, which becomes 

 active after the secretion has passed into the intestine. In 

 the minced gland the change appears to take place through 

 the agency of air and moisture. There is a marked differ- 

 ence in the activity of the glands of different animals, which 

 fact is practically recognized by the manufacturers of the com- 

 mercial products. The pancreas of the hog furnishes an en- 

 zymic mixture richer in the starch digesting agents, while the 

 beef pancreas seems to be most active in the digestion of 

 proteins. 



As the proteins are prepared practically for final absorption 

 from the intestine by the action of trypsin, so the remains of 

 the carbohydrates are brought into the proper final condition 

 by the amylopsin and maltase; at any rate the starches are 

 so prepared, and maltose from any source also. But as to 

 cane sugar and milk sugar there appears to be some little 

 doubt, several authors claiming that the pancreas does not con- 

 tain lactase or invertase, but that the changes in these sub- 

 stances, when not already accomplished by the acid gastric 

 juice, take place through the agency of the enzymes of the 

 intestine. 



