DIGESTION. 203 



The action of the pancreatic juice in splitting the fats may be 

 shown in the following way. Shake olive-oil with caustic soda and 

 ether, siphon off the ether and filter if necessary, then shake the 

 ether repeatedly with water and evaporate at a gentle heat. In this 

 way we obtain a residue of fat free from fatty acids which is com- 

 pletely neutral, and which dissolves in acid-free alcohol and is not 

 colored red by alkanet tincture. If such fat is mixed with quite fresh 

 alkaline pancreatic juice or with a freshly-prepared infusion of the 

 fresh gland and treated with a little alkali or with a faintly alkaline 

 glycerin extract of the fresh gland (9 parts glycerin and 1 part soda 

 solution of \% for each gramme of the gland) and some litmus 

 tincture added and the mixture warmed to -|- 37 C., the alkaline 

 reaction will gradually disappear and an acid one takes its place. 

 This acid reaction depends upon the conversion of the neutral fats 

 by the enzyme into glycerin and free fatty acids. 



The splitting of the neutral fats may also be shown more exactly 

 by the following method. The mixture of neutral fats (absolutely 

 free from fatty acids) and pancreatic juice or pancreas infusion is 

 digested at the temperature of the body and treated with some 

 soda and repeatedly shaken with fresh quantities of ether until all 

 the unsplit neutral fats are removed. Then it is made acid with 

 sulphuric acid, after which shake the acid liquid with ether, evapo- 

 rate the ether, and test the residue for fatty acids. 



Another simple process for the demonstration of the fat-splitting 

 action of the pancreas glands is the following (CL. BERNARD). A 

 small portion of the perfectly-fresh, finely-divided gland substance 

 is first soaked in alcohol (of 90$). Then the alcohol is removed as 

 far as possible by pressing between blotting-paper, after which the 

 pieces of gland are covered with an ethereal solution of neutral 

 butter-fat (which may be obtained by shaking milk with caustic 

 soda and ether). After the evaporation of the ether the pieces of 

 gland covered with butter-fat are pressed between two watch-glasses 

 and then gently heated to 37 to 40 C. in this position. After a 

 certain time a marked odor of butyric acid appears. 



The action of the pancreatic juice in splitting fats is a process 

 analogous to that of saponification, the neutral fats being decom- 

 posed, by the addition of the elements of water, into fatty acids and 

 glycerin according to the following formula: CsH^Os-Rs (neutral 

 fat) + 3H 2 = C 3 H 5 .03.H3 (glycerin) + 3(H.O.R) (fatty acid). 

 This depends upon a hydrolytic splitting, which was first positively 

 proved by BERNARD and BERTHELOT. The pancreas enzyme alsa 

 decomposes other esters just as it does the neutral fats (NENCKi). 

 The pancreas-enzyme which decomposes fats has been less studied 



