ABSORPTION AND TRANSPORT OF FATS 153 



ing action of soap by the formation of soap/cholesterol complexes, 728 such 

 changes will not alter the pH-conditioned character of the soap emulsion. 



In seeking the answer as to what systems might be satisfactory within 

 the acid range, Frazer and co-workers 729 examined bile salts, fatty acids 

 (soaps), cholesterol, and monoglycerides, singly, in double, or in triple 

 combination. The only combination which met all the requirements, i.e., 

 stability over a long period of time at a pH on the acid side of 7.0, was the 

 triple combination fatty acid/bile salt/monoglyceride. The presence of 

 monoglycerides in intestinal contents had been proved earlier by Frazer 

 and Sammons, 647 who showed that glycerol was absent from the in vitro 

 digest of pancreatic lipase and olive oil over a five-hour period, although 

 the acetyl value, which is indicative of the free alcohol groups, rose from 5 

 to 64 during that interval. Similar proportions of the lower glycerides 

 were obtained in material recovered from the intestines of rats sixteen 

 hours after large doses of fat had been administered. 



In further investigations of the nature of the emulsions, Elkes, Frazer, 

 et al. 730 analyzed their compositions. The presence of fatty acids, triglyc- 

 erides, diglycerides, and monoglycerides in intestinal emulsions could be 

 demonstrated, but no phospholipid was present. 731 The latter finding was 

 supported by the fact that the lecithinase D obtained from Clostridium 

 welchii (gas bacillus) did not affect the emulsion. The flocculation pattern 

 was that of simple negatively charged particles. 621 - 731 These later studies 

 would seem to add further support to the Frazer Partition Theory by fur- 

 nishing new evidence that the fatty acid/bile salt/monoglyceride complex is 

 the only emulsion system which will function under the conditions existing 

 in the small intestine. 



b'. Hydrolysis: The most crucial part of the Partition Theory is the 

 assumption that the hydrolysis of triglycerides in the intestine is a 

 partial one. Without supporting evidence for this fact, the whole hy- 

 pothesis would be most insecure. 



In considering the effectiveness of lipase in bringing about the splitting 

 of triglycerides, the most important consideration is the time factor. 

 Although it is frequently stated that the peak of fat absorption occurs six 

 hours after a meal containing fat is taken, this is true only when excessive 

 amounts of this foodstuff are consumed. Ordinarily, with an intake of 

 30 g., the maximum lipemia obtains within 2.5 to 3 hours, and the normal 



728 J. H. Schulman and E. G. Cockbain, Trans. Faraday Soc, 36, 651-661 (1940). 



729 A. C. Frazer, J. H. Schulman, and H. C. Stewart, /. Physiol, 103, 306-316 (1944). 



730 J. J. Elkes, A. C. Frazer, J. H. Shulman, and H. C. Stewart, Proc. Roy. Soc. Lon- 

 don, A184, 102-115(1945). 



731 J. J. Elkes and A. C. Frazer, J. Physiol, 102, 24P-25P (1943). 



