458 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 seerns 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 filled 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 Lieberklihn, 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-fuchshi, 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. 194 ; Internat. Monatschr. f. Anat, u. HistoL, Leipzig, 1885, Bd. ii. S. 6 ; Arch. f. d. 

 yes. Physiol., Bonn, 1884, Bd. xxxiii. S. 513. Schafer's observations were chiefly made 

 upon the frog and rat. 



2 Ibid., Bd. xxxiii. S. 532. 



3 Internat. Monatschr. f. Anat. u. HistoL, Leipzig, 1885, Bd. ii. S. 6. 



4 Arch f. d. ges. Physiol., Bonn, 1888, Bd. xliii. Supp. Heft, S. 82. 



5 It should, however, be pointed out, that after prolonged treatment with osmic acid, 

 fats tend to become insoluble in these fluids. 



6 Arch.f. d. ges. Physiol. , Bonn, 1888, Bd. xliii., Supp. Heft, S. 103, figs. 39 and 40, plate iv. 



7 Ibid., S. 88. 



