86 CELL-CONTENTS AND CELL-WALLS. 



temperature not above 30 C., or simply let it dry in the 

 air without applying heat. Extract the dried material 

 with cold water, and after repeated shaking filter it into a 

 bottle labelled A. 



(B) To the residue from A add some 2 per cent, 

 caustic soda solution; shake repeatedly, and filter into a 

 bottle labelled B. 



Extract A contains soluble proteins, proteoses, peptones, 

 amido compounds. Apply the tests for these. 



Extract B contains proteins insoluble in water but 

 soluble in dilute alkali. Apply the tests for proteins. 



To test for the presence of enzymes in the watery extract 

 (A) add portions of the extract to (1) starch solution 

 test for diastase ; (2) albumin solution test for pepsins 

 and trypsins ; (3) peptone solution test for erepsin ; 

 (4) neutral olive oil test for lipase ; (5) salicin solution 

 test for emulsin. In each case set up a control, adding 

 extract which has been boiled to destroy any enzyme pre- 

 sent ; place the test-tubes in a bath, or in a beaker of 

 water kept at 40 C., for an hour, and test (1) for reducing 

 sugar, (2) for peptone, (3) for tyrosin, (4) for free fatty 

 acid and glycerine, (5) for glucose and saligenol. 



