200 TEXT-BOOK OF PHYSIOLOGY. 



animal rabbit by Kiihne and Lea. They observed that as soon 

 as digestion set in, the granules of the broad inner zone began to 

 pass toward the lumen of the acinus and to gradually disappear as 

 the secretion was poured out, while the outer zone increased in 

 width until almost the entire cell became clear and homogeneous. 

 (See Fig. 84.) After secretion ceased the granules again made their 

 appearance, the result, in all probability, of metabolic activity. 



Physiologic Action of Pancreatic Juice. Experimental in- 

 vestigations have demonstrated the fact that^pancreatic juice is the 

 most complex in its physiologic action of all the digestive fluids^ In 

 virtue of its contained enzymes, pancreatic juice acts : 



1. On starch. When normal pancreatic juice or a glycerin 

 extract of the gland is added to a solution of hydrated starch, the 

 latter is speedily transformed into maltose, passing through the inter- 

 mediate stage of dextnn. The process is in all respects similar to 

 that observed in the digestion of starch by saliva. Pancreatic juice, 

 however, is more energetic in this respect than saliva. The enzyme 

 which effects this change is termed amylopsin. When the starch 

 which escapes salivary digestion passes^TfTtne small intestine and 

 mingles with pancreatic juice, it is very promptly converted into 

 maltose by the action or in the presence of this enzyme. 



2. On proteid. When proteid bodies are subjected to the action 

 of pancreati(Tjuice, they are transfn^ppH intn p?ptrvnpg wn ich do not 

 differ in essential respects from those formed by gastric juice. The 

 intermediate stages, however, are believed to be somewhat different. 

 The enzyme which effects this change is termed trypsin. 



When fibrin, for example, is added to trypsin t!ra- sSlfrtion rendered 

 alkaline by sodium carbonate, it does not swell up and become trans- 

 lucent, as it does when treated with hydrochloric acid and pepsin. 

 On the contrary, it becomes corroded on the surface, fragile, and in a 

 short time undergoes solution. The first product is a compound 

 termed alkali-albumin. After solution has taken place, various chemic 

 changes are initiated which eventuate in the production of peptone and 

 certain nitrogenized bodies, leucin, tyrosin, aspartic acid, etc. The 

 intermediate stages in this process have not been satisfactorily deter- 

 mined. At no time during artificial pancreatic digestion is there any 

 evidence of the presence of the primary proteoses (proto-albumose 

 and hetero-albumose). The secondary proteoses (deutero-albumose) 

 are usually present. It will be recalled that when the amphopeptone 

 of peptic digestion is subjected to the action of trypsin a portion of it, 

 approximately one-half, is decomposed into leucin and tyrosin, while 

 the remaining half retains its peptone characteristics. This latter 

 portion is termed antipeptone; the former portion is termed hemi- 

 peptone, though it has never yet been isolated and is therefore only 

 a hypothetic compound. 



