194 W. E. BLOOR 



so that by the time the fat reaches the intestine a considerable amount of 

 free fatty acid is present. The free fatty acid is neutralized by the alkali 

 carbonates of the various secretions that find their way into the intestine, 

 forming soaps -which quickly and completely emulsify the remaining 

 fat, thus preparing it for rapid digestion by the lipases. Added to the 

 orher factors is the continuous absorption which removes the products of 

 hydrolysis from the field of action, thereby in a balanced reaction like 

 the hydrolysis of a fat, providing the best conditions for rapid and com- 

 plete action. Under these conditions it is probable that the amount of 

 fat which escapes digestion is negligibly small. 



The Absorption of /' from the Intestine. The manner in which 

 the fat leaves the intestine has received its share of experimentation and 

 speculation. The earlier belief was that the fat was absorbed as such in 

 emulsified form, based largely on the observation that emulsions are often 

 found in the intestine during fat absorption and that the fat in the chyle 

 is also in the emulsified form. While it was known that the chyle fat 

 was in general much more finely divided than the intestinal fat, that 

 objection might be explained away by the assumption that the particles 

 were absorbed only as they reached a fine state of division. Further evi- 

 dence believed to point in the same direction is that large amounts of 

 characteristic food fat may be laid down in the fat depots of animals with 

 slight change. Another argument, later shown to be faulty, was that if 'a 

 stained fat were fed similarly stained fat appeared in the chyle. An 

 additional bit of evidence in favor of absorption of unchanged fat was 

 the observation of Ravenel that bacteria may be carried through the 

 intestinal wall if fat is fed along with them when they do not pass through 

 otherwise. The fact that other foodstuffs such as the carbohydrates and 

 proteins were known to be absorbed in water soluble form and that much 

 free fatty acid and soap were to be found in the intestine during fat diges- 

 tion led Kiihne to put forward the hypothesis that fats also were absorbed 

 in water soluble form, being first split in the intestine and then re- 

 synthesized in passing through the intestinal wall. This hypothesis 

 brought forth a large amount of experimental work which finally resulted 

 in practical adoption as the most satisfactory explanation of the method 

 of transference of fat from the intestine to the blood. 



The earliest conclusive work on the subject was that presented by 

 Munk (a) (1891), who, making use of a human patient with a chyle fis- 

 tula, was able to show that fatty acids and esters of the fatty acids with 

 alcohols other than glycerol were absorbed, appearing in the chyle not as 

 these substances but as neutral triglycerids. He was followed by v. Wal- 

 ther, who confirmed his results with fatty acids or soaps, and more recently 

 by Frank (c) (1S9S), with ethyl esters of the fatty acids and Bloor (a) 

 (1913) with an optically active niannite ester of a fatty acid. In all these 

 cases the evidence indicated that no trace of the substance fed appeared in 



