FATS LECITHIN CHOLESTEROL. 105 



saponified, while another portion, consisting of finely divided globules, is 

 absorbed in this state. In spite of numerous investigations a clear con- 

 ception of fat digestion is not yet at hand. Radijewski, 1 in investigations 

 with dogs, showed that soap can be assimilated, and converted into fats. 

 To show that a complete hydrolysis of fat occurs, the work of Connstein * 

 has been cited. He fed a dog with lanolin. Tm's is not saponified by the 

 usual saponifying agents, although it forms an extremely fine emulsion 

 when rubbed up with water. 97 . 5 per cent of the lanolin administered 

 in this form was evacuated unchanged, in the faeces. 



Many fats require complete decomposition to make them available for 

 assimilation. Such fats are the ones whose melting-points lie above the 

 body-temperature. I. Munk 3 has shown that 90 per cent of mutton- 

 tallow, melting at 49, was utilized by dogs. Spermaceti, melting at 53, 

 was also assimilated. The rapidity and extent of digestion are certainly 

 influenced by the melting-points of the fats. The fats of lowest melting- 

 points are utilized soonest and in the largest quantities. 



Microscopic investigations have been made in the attempt to estimate 

 the extent of the fat decomposition in the alimentary tract, by determin- 

 ing at what place in the epithelial cells and walls of the intestine the fat 

 is present as such. In the first place we must state that the walls of the 

 intestine are a large factor in the assimilation of fats. In it the fatty acids 

 and glycerol molecules are reunited so that large quantities of fatty acids 

 and glycerol are prevented from entering the body. I. Munk 4 has shown 

 this very clearly. He fed dogs with pure fatty acids, and found an 

 increase in the neutral fat, but no free fatty acid in the lymph taken from 

 the thoracic duct. 



That the synthesis takes place in the walls of the intestine is certain 

 from the investigations of Perewoznikoff. 5 He fed fatty acid and glycerin 

 to a fasting dog, and obtained in the epithelial cells of the intestine the 

 same microscopic appearances as when he administered fats. Will 6 and 

 C. A. Ewald 7 even observed a fat formation from glycerol and fatty acids 

 in a dissected intestine. Microscopical studies of fat assimilation have 

 not given uniform results. Some observers have found the basal edges 

 of the intestinal epithelial entirely homogeneous and free from fat globules 

 during the absorption of the fats, and could indicate their presence only 



1 Virchow's Arch. 43, 268 (1868). 



2 Connstein: Arch. Anat. Physiol. 1899, 30; Die med. Woche, No. 15, 1900. 



3 Virchow's Arch. 95, 407 (1884). Arnschink: Z. Biol. 26, 434 (1890). O. Frank, 

 Arch. Anat. Physiol. 1894, 308. F. Miiller: Z. klin. Med. 12, 45 (1887). 



4 Virchow's Arch. 95, 431 (1884); ibid. 123, 230 and 484 (1891). 



5 Zentr. med. Wissensch. 1874, 851. 

 e Pfliigers Arch. 20, 255 (1879). 



7 Arch. Anat. Physiol. 95, 407 (1884). 



