45S CHEMISTR Y OF THE DIGESTIVE PROCESSES. 
These appearances led Schafer 1 to express the view that the 
lymphoid corpuscles have an important function in taking up the fat 
from the epithelial cells, and carrying it towards and into the lacteal, 
where they set the fat free by disintegrating. No fat particles are, as a 
rule, found between the epithelium and the central lacteal, save such as 
are embedded in lymphoid corpuscles. Nor is there any channel of 
communication between the epithelial cell and the lacteal, as was 
formerly supposed, by which the fat globules might be carried into the 
lacteal. The epithelial cells never penetrate the basement membrane, 
nor are they continued into the cells of the retiform tissue beneath. 
Wiemar 2 admits the presence, during fat absorption, of fat granules in 
the leucocytes, but from the small amount of fat so found, compared 
with that in the epithelial cells, considers that the leucocytes can only 
be of secondary importance. In this connection it should be noted that 
Schafer 3 has pointed out that the relative amount of fat granules in 
leucocytes and epithelial cells varies with the activity of absorption. 
" When the absorptive activity is feeble, or when the amount of fat in 
the chyme is relatively small, there may be little or no fat in the 
columnar epithelial cells, although the amoeboid cells between them may 
be gorged with fat granules. In frogs fed with lard in the spring, 
fatty globules are still abundant in the columnar epithelial cells on the 
eighth day after the feeding, whereas, in frogs similarly fed in November, 
the greater part of the fat was discharged per anum, by the third day, 
very little being absorbed, and what was being taken up during that 
time was only to be found in the amoeboid cells, none at all being 
present in the epithelial cells themselves." This seems to indicate that, 
when the rate of absorption is slow, the amoeboid cells are able to keep 
pace with it, but when the supply is too abundant for this, the columnar 
cells act as temporary storehouses, and become rilled with granules, 
which are afterwards carried off by the amoeboid cells. 
Heidenhain 4 ascribes only a secondary importance to the leuco- 
cytes. He gives as grounds for this opinion — (1) That in newly-born 
puppies, which have already sucked, and in which milk absorption is 
going on, there are scarcely any leucocytes present in the epithelium, so 
that there is no constant connection between fat absorption and the 
presence of leucocytes. (2) Leucocytes containing granules, which stain 
black with osmic acid, are to be found in the crypts of Lieberkuhn, into 
which fat cannot enter from the intestine. (3) The material which is 
stained black with osmic acid is chiefly something else than fat, since 
it stains with acid-fuchsin, and cannot be washed out of adhesively 
mounted sections by ether or xylol. 5 Heidenhain 6 admits, however, 
that in the guinea-pig fat is undoubtedly present in considerable 
quantity in the amoeboid cells during fat absorption. 
Heidenhain 7 still adheres to the emulsion theory of absorption, but 
1 Quain's "Anatomy," 8th edition, 1876, vol. ii. p. 363; " Pract. Histology," 1876, 
p. 104 ; Lilcniat. Monatschr. f. Juat. v. Hislol., Leipzig, 1885, Bd. ii. S. 6 ; Arch. f. d. 
ges. Physiol., Bonn, 1884, Bd. xxxiii. S. 513. Schafer's observations were chiefly made 
upon the frog and rat. 
- Ibid., Bd. xxxiii. S. 532. 
3 Internal. Monatschr. f. Anat. u. Histol., Leipzig, 1885, Bd. ii. S. 6. 
4 Archf. d. ges. Physiol.., Bonn, 18S8, Bd. xliii. Supp. Heft, S. 82. 
5 It should, however, he pointed out, that after prolonged treatment with osmic acid, 
fats tend to become insoluble in these fluids. 
6 Arch./, d. ges. Physiol. , Bonn, 1888, Bd. xliii. , Supp. Heft, S. 103, figs. 39 and 40, plate iv. 
7 Ibid., S. 88. 
