8o PRACTICAL PHYSIOLOGY. [X. 



(r.) For most experiments use the " liquor pancreaticus " of 

 Benger, or of Savory & Moore, or Burroughs, Wellcome & Co. 



{d.) Weigh the pancreas taken from a pig just killed, rub it up with sand in 

 a mortar, and add i ec. of a i per cent, solution of acetic acid for every gram 

 of pancreas. Mix thoroughly, and after a quarter of an hour add lo cc. of 

 glycerin for every gram 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. The 

 extraction must be done in an ether fat-extracting apparatus; and as the 

 process is somewhat tedious, it is better to buy the substance. It can be 

 obtained from Dr. Grlibler of Leipzig. Extract the dry pancreas powder with 

 five parts of a .2 per cent, solution of salicylic acid, and keep it at about 40° C. 

 for eight or ten hours. Use 20 grams of the dry pancreas to 100 cc. of 

 salicylic acid fluid. Strain it through muslin, and press out all the fluid 

 from the residue. The hands must be well washed, as pancreatic digests are 

 so liable to undergo putrefaction. It is well to cover the vessel with paper 

 moistened with an alcoholic solution of thymol. A dense, tough, elastic 

 residue is obtained. Re-extract the latter for several hours at 90° C. with 

 sodic carbonate solution (.25 per cent,\ adding a few drops of alcoholic solu- 

 tion of thymol. 1- iljer the first extract and allow it to stand. Very probably 

 a large mass of crystals of tyrosin will separate. Filter off the deposit and 

 mix the salicylic and alkaline extracts. The extract has only proteolytic pro- 

 perties. I find this extract acts much more energetically than those prepared 

 in other ways. What remains after the action of salicylic acid and sodic car- 

 bonate contains leucin and tyrosin. 



(/.) Solution of Pancreatic Enzymes. — Apart from the fat-splitting ferment 

 or enzyme, the other ferments are readily extracted from the gland — under 

 certain conditions by (i.) glycerin, (ii.) saturated watery solution of chloro- 

 form {Roberts), but the chloroform extract interferes with the reaction for 

 grape-sugar. Harris and Gow find that a saturated solution of common salt 

 extracts all the pancreatic enzymes (save the fat-splitting). Roberts found 

 that by extracting the pancreas with a solution containing a mixture of 

 boracic acid and borax a serviceable extract was obtained. 



2. I. Action on Starch (Amylopsin the ferment). 



(a.) To thick starch mucilage in a test-tube add glycerin extract 

 of pancreas or liquor pancreaticus, and place it in a water bath at 

 40° C. Rapidly the starch paste becomes fluid, loses its opal- 

 escence, and becomes clear. Within a few minutes some of the 

 starch is converted through intermediate stages (p. 69) into 

 maltose. Test for sugar (Lesson III. 8, V.). 



(6.) Pancreatic Juice and Bile. — Repeat A, but add a little bile, 

 the starch disappears more quickly. Prove by testing on a white 

 porcelain slab, as in Lesson VIII. 4. 



3. The same conditions obtain as for saliva (Lesson "VTII. 5). 



