BIOLOGICAL CHEMISTRY 



from an animal and is stained with osmic acid or other fat 

 stain it is found that the portion of the cells next to the intes- 

 tinal contents is unstained, but that fat drops are found in the 

 deeper parts of the cells. The drops are largest in the central 

 portion of the cell, and they become smaller towards the base 



of the cell. The fat globules can be 

 traced beyond the cell through the 

 connective tissue to the lymphatic 

 vessels which lie close to the mucous 

 membrane. In the lymphatic vessels 

 the fat forms a milk -like emulsion 

 (chyle), and during absorption of fat 

 the lymphatics can be seen as white 

 lines stretching away from the in- 

 testine. The fat passes with the 

 lymph to the receptaculum chyli 

 and thence up the thoracic duct to 

 enter the blood stream at the root of 

 the neck. In the blood stream the 

 fat is carried away and soon disap- 

 pears, although after a meal rich in 

 fat there may be a slight opalescence 

 of the blood plasma indicating the 

 presence of minute particles of 

 suspended fat. Within twelve hours 

 after a meal containing fat at least 

 sixty per cent, of the absorbed fat 

 can be recovered from the thoracic 

 duct, so there is a remainder which 

 of may be carried away from the intes- 

 tine in the blood stream.* 



By chemical analysis it is possi- 

 ble to show that during absorption 



A Surface; epithelium^iBlood the fatty add ig com bined with gly- 



cerine to form fats. The contents of 

 the intestine consist mainly of 

 saponified fat. This can be shown 

 by analysis of the material scraped from the surface 

 of the mucous membrane after a meal rich in fat. 

 The fat emulsion collected from the lymphatics (lacteals) 

 consists mainly of neutral fat and analysis of the mucous 

 membrane shows less neutral fat and more free fatty acid.f 



* I. Munk, Virchow's Arch., 1891, vol. 123, p. 230. 

 f B. Moore, Proc. Roy. Soc., 1903, vol. 72, p. 134 ; I. Munk, Arch' 

 f. path. Anat. u. Physiol,, 1880, vol. 80, p. 17. 



FIG.''' 25. Diagram 

 intestinal villi showing 

 channels of absorption 

 of food materials. 



C Lacteal 

 lymph vessels. 

 (Copied from " Elementary Physi 

 otogy," Huxley. Macmillan.) 



