CHEMISTRY OF DIGESTION AND NUTRITION. 243 



of the proteid of the food receives its final preparation for absorption in the 

 small intestine, under the influence of this enzyme. 1 



Albuminoids. Gelatin and the other albuminoids are acted upon by 

 trypsin, the products being similar in general to those formed from the pro- 

 teids. As stated on page 235, pepsin carries the digestion of gelatin mainly to 

 the gelatose stage ; trypsin, however, produces gelatin peptones. It seems 

 probable, therefore, that the final digestion of the albuminoids also is effected 

 in the small intestine. 



Amylopsin. The enzyme of the pancreatic secretion which acts upon 

 starches is found in extracts of the gland, made according to the general 

 methods already given, and its presence may be demonstrated, of course, in 

 the secretion obtained by establishing a pancreatic fistula. The proof of the 

 existence of this enzyme is found in the fact that if some of the pancreatic 

 secretion or some of the extract of the gland is mixed with starch paste, the 

 starch quickly disappears and maltose or maltose and dextrin are found 

 in its place. Amylopsin shows the general reactions of enzymes with rela- 

 tion to temperature, incompleteness of action, etc. Its specific reaction is its 

 effect upon starches. Investigation has shown that the changes caused by it 

 in the starches are apparently the same as those produced by ptyalin. In 

 fact, the two enzymes ptyalin and amylopsin are identical in properties as 

 far as our knowledge goes, so that it is not uncommon, in German liter- 

 ature especially, to have them both described under the name of ptyalin. 

 The term amylopsin is convenient, however, in any case, to designate the 

 special origin of the pancreatic enzyme. As to the details of its action, it is 

 unnecessary to repeat what has been said on page 223. The end-products 

 of its action, as far as can be determined from artificial digestions, are a sugar, 

 maltose (C 12 H 22 O 11 ,H 2 O), and more or less of the intermediate achroodextrins, 



1 The details of the cleavage of the proteid molecule under the influence of pepsin 

 and trypsin are obviously not yet completely worked out. The general idea of Klihne 

 is given briefly in a foot-note on page 231. An important modification of the original 

 conception is represented in a theoretical schema given by Neumeister, which is here 

 reproduced. According to this diagram, each proteose, as well as the peptone produced 

 in an ordinary digestion, contains both hemi- and anti- groups, and is therefore an 

 ampho- compound. The relative amount of hemi- or anti- substance present at each 

 stage is indicated by thick or thin lines as the case may be. While proto-proteose and 

 the deutero-proteose and peptone arising from it are mainly composed of the hemi- 

 group, hetero-proteose and its subsequent stages consist chiefly of the anti- grouping. 

 The resistant compound, known as anti-albumid, which is split off from the proteid 

 molecule in greater or less quantity, seems to have only the anti- grouping; so far as it 

 can be converted to peptone, it yields only anti-peptone. 



f Proteid molecule. 



[Hemi- group. Anti- group. J - 



Proto-proteose. Hetero-proteose. 



(Ampho-proteose.) (Ampho-proteose.) Anti-albumid. 



Deutero-proteose. Deutero-proteose. Deutero-proteose. 



(Ampho-proteose.) (Ampho-proteose.) (Anti-proteose.) 



Ampho-peptone. Ampho-peptone. Anti-peptone. 



