FERMENTATION 207 



oil in a test-tube and add a small quantity of 

 pancreatic juice (or a piece of fresh pancreas or 

 extract of pancreas). Test the reaction of the 

 mixture. It is alkaline. Note that a white, 

 creamy liquid forms almost immediately. This 

 " emulsion " is composed of a multitude of small 

 fat globules. 



Test the reaction again. It gradually becomes 

 acid. 



It is evident that under the influence of the 

 pancreatic juice the fatty matter is not simply 

 finely divided and emulsified, but that it has also 

 been modified chemically. 1 



In order to study the splitting of neutral fats 

 by lipase, a ferment found in the pancreatic juice, 

 it is necessary (1) to prepare a perfectly neutral 

 fat, and (2) to recognize the fatty acid as soon as 

 it is set free. 



Preparation of Neutral Fat. Shake commer- 

 cial olive oil (which always contains fatty acid) 

 for two hours at 95 C. in a separating funnel 

 with a saturated solution of barium hydroxide. 

 Allow the mixture to stand until the oil sepa- 

 rates from the hydroxide. Eemove the hydrox- 

 ide. Filter the oil. 



The Emulsion Test for Fatty Acid. Brucke's 



1 Bernard : Comptes rendus de 1'academie des sciences, Paris, 

 1849, xxviii, p. 250. 



