ABSOKPTIO.Y OF FA TS. 46 1 
studied. It was found that food passed very rapidly through the alimentary 
canal without much modification, scarcely any fal was absorbed, but it was 
nearly all converted into fatty acid. 
These varied results may be summed up as showing that both the 
pancreatic juice ami the bile are powerful aids in the digestion and 
absorption of fats, but neither is absolutely indispensable. 
The view to be taken of the part played by bile ami pancreatic juice 
in fat absorption must naturally vary with the view held as to the form 
in which fat is absorbed. 
1. It may be urged that, in the absence of pancreatic juice, a sufficient 
supply of fatty acid is not set free for emulsification of the remainder. 
Since bile (or bile salts) very much hastens the fat-splitting action of 
pancreatic juice, 1 the absence of bile would have a very similar effect to 
that of pancreatic juice itself. A serious objection to this explanation 
lies in the fact that in defective absorption, due to the absence of either 
bile or pancreatic juice, nearly all the unabsorbed fat is found in the 
faeces as free fatty acid. 
It might be claimed that this fat-splitting, probably by bacterial 
action, takes place much lower down in the intestine, at a less favoural.de 
position for absorption, and that a considerable part of the intestine is 
traversed before a sufficient amount of fatty acid is formed. But in the 
faeces as much as 80 per cent, of the total fat is as free fatty acid, while 
only about 5 per cent, is required for spontaneous emulsion ; besides, the 
fat of the food contains nearly sufficient fatty acid to begin with, so that 
this contention has little weight. 
2. Another view which has been held is, that in the absence of either 
bile or pancreatic juice the intestinal reaction is acid, so that no emul- 
sion can take place, and hence the fat cannot be absorbed. It is not, 
however, claimed that such an acid reaction is due to free hydrochloric 
acid, since the remaining alkaline secretions are still more than sufficient 
to neutralise this, and active fat absorption has often been observed in 
presence of an acid reaction due to organic acids. 
3. It has been supposed that the absence of the proteid of the 
pancreatic juice has an unfavourable effect on the formation of an 
emulsion ( Minkowski). 
4. A theory advanced by v. Wistinghausen 2 was that the bile aided 
fat absorption by mechanically wetting the epithelial cells with a fluid 
which rendered the passage of the fat easier. He claimed that oil 
stood higher in capillary tubes wetted with bile than in similar tubes 
wetted with water, and that oils or melted fats passed more rapidly 
through a membrane wetted with bile than through one wetted 
with water. These results have not, however, been confirmed by other 
observers. 3 
5. It has also been supposed that the bile directly stimulates 
(chemically) the epithelial cells of the intestine to increased fat absorp- 
tion, and that in the absence of the bile this stimulus is absent. Under 
these conditions the epithelial cells either do not absorb fat as an eniul- 
1 Rachford, Jowrn. Physiol., Cambridge and London, 1891, vol. x'ii. p. 87. 
-Translation in Arch. f. A, tat. a. Physiol., Leipzig, 1873, S. 137, by J. Steiner. See 
also Scbiff, Untersueh. z. Naturl. d. Mensch. v. d. Thiere, 1857, Bd. ii. S. 345; Heiden- 
hain, Arch. f. d. ges. Physiol., Bonn, 188S, Bd. xliii. Supp. Heft, S. 91. 
3 Groper, Arch../. Anal. u. Physiol., Leipzig, 1889, S. 505. 
