454 CHEMISTR Y OF THE DIGESTIVE PROCESSES. 
absorption in the form of soaps, is that urged by I. Munk, namely, the 
enormous quantity of alkali which would be required for such a purpose. 
Munk x reckons that to so combine with the fatty acids of 200 grins, of 
fat, about 40 grins, of sodium carbonate (Na,C0 3 ) would be required. 
Now a dog of 25 kilos, can easily digest from 200 to 350 grms. of fat 
in twenty-four hours. 2 Supposing only 200 grms. are digested, and that 
all this is absorbed as soaps and glycerin, about 40 grms. of sodium 
carbonate will be required for the purpose ; now the total blood only 
contains, in such an animal, alkali equivalent to 6 grms. of Na.,C0 3 ; if 
the other fluids of the body be supposed to contain an amount of alkali 
equivalent to another 6 grms. of sodium carbonate, the total alkalinity is 
equivalent to that of 12 grms. of sodium carbonate. 3 Therefore, to 
suffice for the absorption of the fatty acids as soaps, from three to four 
times the total alkali of the body must pass out in the intestinal 
secretions, and be reabsorbed with the fatty acids, during twenty -four 
hours. This is obviously impossible ; therefore the fats are not absorbed 
as soaps and glycerin. 
This objection of Munk loses, however, most of its weight, when 
the probable processes taking place, in case fats are absorbed as soaps 
and glycerin, and synthesised again to neutral fats in the epithelial 
cells, are carefully considered. In the synthesis of fat from soap and 
glycerin within the cell, alkali is again set free in exactly equal amount 
to that in which it was used up in the intestine, and this alkali must be 
got rid of by the cell in some manner. Why should it not be sent back 
again into the intestine, and act as a carrier to a fresh quantity of fatty 
acid as soap into the cell ? In such a fashion a very small amount of 
alkali would suffice to explain the carriage of all the 200 grms. of fat as 
dissolved soap and dissolved glycerin into the epithelial cells. 
It might possibly be further objected that soaps are only present in 
small quantity in the intestinal contents. But this applies also to 
alkali albumin, propeptones, peptones, and sugars ; in fact, to all the 
products of the digestion of both proteids and carbohydrates. If soaps 
are normally absorbed by the epithelial cells, it is probable that these 
cells possess a selective capacity for soap absorption, as they do for many 
other products of digestion, and hence that the soaps are absorbed as 
they are formed, and never allowed to accumulate in appreciable 
quantity in the intestine. 
There is, then, no proof that soaps cannot be formed in the intestine, 
nor is there any impossibility or improbability in the way of all the fats 
being first decomposed into fatty acids, then converted into soluble 
soaps and absorbed as such. 
Theory of absorption as dissolved fatty acids. — Another theory is, that 
the fats are absorbed in the form of dissolved fatty acids. 
The fatty acids of the fats are practically insoluble in water, but are 
soluble to a certain extent in bile, the solubility increasing with rising temper- 
ature. Strecker 4 stated, in 1848, that taurocholic acid possesses the property 
of dissolving fat, fatty acids, and cholesterin in considerable quantity. This 
fact is mentioned by Strecker in connection with the difficulties attending the 
1 Virchows Archiv, 1880, Bd. lxxx. S. 11 ; 1884, Bd. xcv. S. 40S. 
2 Pettenkofer and Voit, Ztsehr. f. Biol., Mtinchen, 1873, Bd. ix. S. 30. 
3 These figures must only be taken as argumentative data, overstepping the truth, and 
not as truly indicating the total alkalinity. 
4 Ann. d. Chem., Leipzig, 1848, Bd. lxv. S. 29. 
