440 Messrs. B. Moore and D. P. Kockwood. On the 



power, dissolving 1 to 5 per cent, of the fat of beef suet at 39 C 

 The solution becomes viscid, semi-fluid, or completely solid on cooling, 

 arid redissolves'on warming again. With the filtered contents of the 

 intestine of the pig and rabbit similar results were not obtained, but 

 the fat became altered, being in part converted into fatty acids, and 

 in part giving rise to a voluminous precipitate. 



Simultaneous Action of Pancreas and Bile on Fats. 



Finely minced, fresh dog's pancreas (1 gram) was added to bile 

 (10 c.c.), and then the fat of beef suet (0*25 gram) ; the fat com- 

 pletely dissolved in three hours at 40 C. ; on cooling, the solution 

 became turbid, and finally semi-solid. In a control experiment, 

 pancreas alone decomposed fat into fatty acids, but did not dissolve it. 



The solubilities stated above are quite sufficient to account for the 

 removal of all the fat of the food from the intestine as dissolved fatty 

 acid, since they exceed the concentrations found in the intestine of 

 other materials, such as sugars and albumoses, which are removed 

 in solution. Other experiments, however, on the reaction of the 

 intestine during fat absorption, lead us to think that all the fat is not 

 removed as dissolved fatty acids, but that these are replaced to a 

 variable extent (in some animals, to. a very large extent or completely) 

 lay dissolved soaps. 



Reaction of Intestinal Contents during Fat Absorption. 



We have determined the reaction of the contents of the dog's 

 small intestine during fat absorption, from pylorus to caecum, to 

 various indicators, litmus, methyl-orange, and phenolphthalein, and 

 cannot agree with the statement of some other experimenters, that it 

 is acid throughout.* In sixteen experiments on this animal we only 

 once found the reaction acid to litmus up to the caecum, and this was 

 an obviously poor experiment, in which the intestine was almost 

 empty. The reaction to litmus at the pylorus is neutral, faintly acid, 

 or faintly alkaline ; from here onwards the acidity increases, reaches 

 a maximum about the middle of the small intestine, and then 

 becomes less acid, to change to alkaline at a point situate two-thirds 

 to three-fourths of the way along the intestine ; from this point on 

 to the caecum the alkalinity increases. f The reaction to methyl- 

 orange and phenolphthalein explains this ; the intestine is alkaline to 

 methyl-orange all the way from pylorus to caecum, and equally com- 



* Cash, 'Arch. f. Anat. u. Physiol.,' 1881, p. 386 ; Munk, 'Zeitsck. f. Physiol. 

 Chem./ vol. 9, 1885, pp. 572, 574. 



t There is usually a reversion to an acid reaction in the large intestine, in "which 

 case the contents of the caecum are almost neutral. 



