450 CHEMISTR Y OF THE DIGESTIVE PROCESSES. 



plasmic processes from the epithelial cells, and one or two l fancied they 

 had discovered such appearances, but their observations have not been 

 confirmed, and are undoubtedly erroneous. If the epithelial cells of the 

 intestine possessed the power of absorbing in bulk fat granules, there 

 is no obvious reason why other food particles, such as granules of 

 starch or proteid, should not be similarly absorbed, but no such 

 absorption has ever been observed, nor are they capable of absorbing 

 finely subdivided granules of coloured matter, such as carmine. 



The mucous membrane of the intestine contains an immense 

 number of lymph corpuscles. 2 These are found not only in the lymph- 

 oid nodules, which occur so abundantly as solitary glands and Peyer's 

 patches, but in the intestinal villi, even between the epithelial cells, where 

 they may approach quite close to the fr^e surface, and abundantly in the 

 adenoid tissue underlying them. Now, such lymph corpuscles are capable 

 of enveloping and so absorbing fat granules, and have been credited with 

 an important function in the removal of fat from the intestine by so 

 doing. It was stated by Zawarykin 3 that when fat absorption is going 

 on, fat granules are to be found only in these lymphoid cells and not in 

 the cells of the columnar epithelium. This statement is undoubtedly 

 erroneous, for it is easy, from an animal killed after a meal rich in fats, 

 to obtain sections showing the columnar cells filled with fat globules. 



" During active fat absorption, especially if the amount of fat in the 

 chyme is relatively large, the columnar epithelial cells become filled 

 with globules of fatty matter. These globules are of variable size, and 

 may occur in all parts of the cell, but they are generally largest in the 

 part between the nucleus and the thickened border, and are often quite 

 small near the attached end of the cell." 4 



It is evident, then, that the greater part of the fat, if not the whole 

 of it, must be absorbed by the epithelial cells from the intestine. It 

 is also very improbable that these cells take up the fat in the form of 

 an emulsion. As has already been stated, the structure of the cell is 

 unsuitable for such a function, and, in addition, fat granules have never 

 been observed in the broad striated border. This almost amounts to a 

 demonstration that the fat passes through the border of the cell in some 

 soluble form, and is afterwards thrown down in a particulate form, as the 

 result of a process of cell metabolism. 



Emulsion theories of fat absorption are therefore being gradually 

 replaced by theories of absorption in solution. These theories must 

 next be discussed, but before doing so reference may be made to another 

 emulsion theory of fat absorption introduced by Munk. 



Theory of I. Munk. Munk 5 showed that fatty acids can be 

 emulsified under exactly the same conditions as rancid fats, and further 

 that these fatty acids are capable of absorption, and can completely take 

 the place in the animal economy of neutral fats, being in great measure 



1 v. Thanhoffer, Arch. f. d. ges. PhysioL, Bonn, 1874, Bd. viii. S. 391 ; Fortuuatow, 

 ibid., 1877, Bd. xiv. S. 285. 



2 These wandering cells ( Wanderzelleri) were first described as occurring in the epithelium 

 by Eberth (Wurzb. med. Ztschr., 1864, S. 23); Arnstein (Virchwfs Archiv, 1867, Bd. 

 xxxix. S. 537) first mentioned the presence of fat granules in them. 



s Arch.f. d. ges. PhysioL, Bonn. 1883, Bd. xxxi. S. 231. 



4 Schafer, Internal. Monatschr. f. Anat. u. HistoL, Leipzig, 1885, Bd. ii. S. 6. 



5 VerJiandl. d. BerL med. Gesellsch., March 1879 ; Arch. f. Anat. u. PhysioL, Leipzig, 

 1879, S. 371 ; Virchows Archiv, 1880, Bd. Ixxx. S. 10; ibid., 1884, Bd. xcv. S. 409; Ztschr. 

 f.physiol. Chem., Strassburg, 1885, Bd. ix. S. 568; Arch. /. Anat. u. PhysioL, Leipzig, 

 1890, Supp. Bd., S. 138. See also v. Walther, ibid., 1890, S. 329. 



