110 



II. DIGESTION AND ABSORPTION OF FATS 



of pH on the surface tension of several fatty acids in sodium glycocholate 

 solutions is illustrated in Figure 4. 



Verzar and Kuthy 513 subscribed to the importance of choleic acid for- 

 mation in the case of desoxycholic and apocholic acids, and postulated an 

 analogous behavior in the case of glycocholic acid. It was shown that fatty 

 acids give a clear solution in the presence of conjugated bile salts when the 

 concentration is low but that, when a greater concentration of fatty acid 

 obtains, the solution becomes milky. These results are interpreted as indi- 

 cating that conjugating bile acids form definite molecular complexes at low 



220 



210 



c» 200 



a. 

 o 



-O190 



o 

 t 180 



.O 



B 

 Z170 



J GO 



Fig. 4. Surface tension of different fatty acids in glycocholic acid solu- 

 tion as influenced by pH. 564 



concentrations of fatty acids, while at higher concentrations of the fatty 

 acids the turbid solutions result, since larger complexes are formed in ad- 

 dition. The solution will be complete so long as the bile acid molecules 

 entirely engulf the fatty acid molecule. It is believed that, at the lower 

 concentration, this condition is satisfied by a ratio of 4 bile salt molecules to 

 one fatty acid molecule; in the higher complexes, the ratio may be 9:4. 

 Thus, it would appear that the choleic acid principle may well be of con- 

 siderable importance in explaining fat absorption. The mere fact that 

 crystalline coordination compounds cannot be demonstrated in the case of 

 conjugated bile acids, as they can with desoxycholic and apocholic acids, is 

 not sufficient justification for discarding the entire hypothesis. The ob- 

 servations of the effect of paired (or conjugated) bile salts on the solution 

 of fatty acids may well be explained by the formation of a complex similar 



