PANCREATIC DIGESTION. 57 



(d.) Weigh the pancreas taken from a dog just killed, rub 

 it up with sand in a mortar, and add 1 cc. of a 1 per cent, 

 solution of acetic acid for every gramme of pancreas. Mix 

 thoroughly, and after a quarter of an hour add 10 cc. of 

 glycerin for every gramme of pancreas. After five days 

 filter off the glycerin extract. The acetic acid is added 

 to convert the unconverted " zymogen " into trypsin. 



(e.) Kiihne's Dry Pancreas Powder. This is obtained 

 by thoroughly extracting a pancreas with alcohol and ether, 

 and drying the residue. It is better to purchase the pre- 

 paration. Extract the dry pancreas powder with five parts 

 of a 1 per cent, solution of salicylic acid, and keep it about 

 40 C. for four or five hours. Filter, and use the filtrate 

 as a glycerin or other extract would be used. It has only 

 proteolytic properties. I find this extract acts much more 

 energetically than those prepared in other ways. 



2. I. Action on Starch. 



(a.) Take thick starch mucilage in a test-tube or beaker, 

 add glycerin extract of pancreas or liquor pancreaticus, 

 and place it in a water-bath at 40 0. Almost immediately 

 the starch paste becomes fluid, loses its opalescence, and be- 

 comes clear. Within a few minutes much of the starch is 

 converted into a reducing sugar or maltose. 



(b.) Test for sugar (Lesson II., 6, IV., b., c.) 



3. The same conditions obtain as for saliva (Lesson VI., 5). 



4. II. Proteolytic Action due to Trypsin, and its Conditions. 



(a.) Take three test-tubes, labelled A, B, and C, fill each 

 half full with 1 per cent, solution of sodic carbonate, and 

 place 5 drops of glycerin pancreatic extract, or liquor pan- 

 'creaticus in each. Boil B, and make C acid with dilute 

 hydrochloric acid. Place in each tube an equal amount of 

 well-washed fibrin, plug the tubes with cotton-wool, and 

 place all in a water-bath at 40 0. 



(b.) Examine them from time to time. At the end of one 

 hour or so, there is no change in B and C, while in A 

 the fibrin is gradually being eroded, and finally disappears, 

 but it does not swell up, the solution at the same time 



