EXCRETION OF LIPIDS BY WAY OF LARGE INTESTINE 341 



unequivocal manner. It was shown that, following the feeding of iodized 

 fat to a dog with a Thiry-Vella fistula, the iodized fat was excreted into the 

 isolated intestinal loop. 



Beumer and Hepner 598 suggested that cholesterol, also, is secreted 

 through the wall of the intestine of the dog. These workers based their 

 conclusions upon the finding that the cholesterol content of normal dogs 

 was higher in the colon than in the ileum. A similar situation was shown 

 to obtain in a bile-fistula dog after a lipid-free meal; it was found that 

 0.21% of cholesterol was present in the dried ileum contents, as con- 

 trasted with a value of 1.25% in the dried colon contents. According | () 

 these investigators, this can only mean that cholesterol has been secreted 

 into the large bowel. Similar results have been reported by Burger 

 and Oeter 601 for man; the cholesterol content of the wall of the sigmoid of 

 cadavers was found to be higher than that in various sections of the wall 

 of the small intestine. These latter workers have likewise interpreted 

 their data as indicating the passage of cholesterol through the wall of the 

 large intestine. 



In addition to cholesterol, the long-chain aliphatic alcohols, which 

 occur in feces, apparently pass through the wall of the intestine into the 

 lumen of the gut, Cetyl or palmityl alcohol, CH 3 (CH 2 ) 14 CH 2 OH, was 

 discovered in feces by Gardner, 33 and its presence in the feces of dogs, cats, 

 and man was demonstrated by Schoenheimer and Hilgetag. 34 The latter 

 workers also proved the presence of this alcohol in the walls of human 

 intestine, in meconium, in the feces of bile-fistula dogs maintained on a 

 fat-free diet, and in operatively prepared sterile cysts of the small and 

 large intestine. Schoenheimer and Hilgetag 34 postulate that cetyl alcohol 

 originates in the body, and is secreted through the mucosa into the lumen 

 of the gut in a manner analogous to that of cholesterol secretion. Evi- 

 dently the origin of the cetyl alcohol occurring in feces must lie in secretion 

 through the walls of the lower gut rather than in the bile or other digestive 

 secretions or in its presence in food. This is indicated by the fact that 

 it is readily absorbed, 36>37 ' 40 and would most certainly not escape such a 

 fate if it were present in the upper part of the intestine where absorption 

 can occur. However, Schoenheimer and Hilgetag 34 suggest that some 

 resorption of cetyl alcohol does take place; under these circumstances, 

 that present in the feces would represent only a fraction of the total alco- 

 hol produced. The identification of palmitic acid as a precursor of cetyl 

 alcohol has been discussed elsewhere (see page 257). The occurrence of 

 octadecyl or stearyl alcohol, CH 3 (CH 2 )i6CH 2 OH, in feces, which has 



601 M. Biirger and H. D. Oeter, Z. physiol. Chem., 182, 141-147 (1929). 



