1903.] Fats accompanying Absorption from the Intestine. 137 



C. A. Ewald* was the first observer who stated that the fresh 

 mucous membrane of the small intestine is capable in vitro of synthe- 

 sizing neutral fat from a mixed solution of soap and glycerine, and 

 recently Hamburger f has published a similar result obtained with the 

 mucous membrane of the large intestine. Both the above observers, 

 however, relied upon the difference in weight between the total ethereal 

 extract, and the weight of fatty acid, as shown by titration with 

 standard alkali, of the ethereal extract, for giving the amount of neutral 

 fat, and did not make direct determinations by saponification with 

 caustic alkali of the amount of neutral fat. Here it is believed by the 

 present writer that they fell into an error, for had such an indirect 

 method been used in the experiments recorded below, similar results 

 to those of Ewald and of Hamburger would have been obtained in 

 many cases. The direct determination by saponification shows, 

 however, that the difference between total ethereal extract and free 

 fatty acid is due not to neutral fat, but to soap dissolved by the 

 ether. I 



Other observers have described synthesis, by extracts of intestinal 

 mucous membrane, and several other tissue extracts, of such esters as 

 ethyl-butyrate, and monobutyrin,)] but no detailed account of these 

 experiments need be given since the conditions of synthesis and hydro- 

 lysis of such esters are probably widely different from those applying 

 to the triglycerides.H 



I. Experiments on tlw composition of the lymph of the mesenteric lymphatic 

 vessels, during fat absorption. 



The lymph was obtained by the method described above from the 

 lac teals of anaesthetised dogs, at a period of 5 7 hours, subsequent to 

 feeding on olive oil. 



The ethereal extract obtained from the lymph was evaporated to 

 dryness, dissolved in hot alcohol and titrated with decinormal sodic 

 hydrate solution using phenol-phthalein as an indicator. 



From the amount of standard sodic hydrate used the percentage of 

 free fatty acid in the ethereal extract was calculated. 



* ' Arch. f. Physiol. u. Anat., Physiol. Abth.,' Suppt. vol., 1883, p. 302. 



t ' Arch. f. Physiol.,' 1900, p. 433. 



Hamburger attempted in his experiments to remove such a source of error, by 

 making a control to which soap was added after digestion, but the amount of soap 

 dissolved appears to vary so as to make this procedure ineffectual, and reliable results 

 can only be obtained by a direct estimation by saponification of the neutral fat. 



Kastle and Loevenhart, * American Chemical Journal/ 1900, vol. 24, p. 491 ; 

 Loevenhart, ' American Journal of Physiology,' 1902, vol. 6, p. 331. 



|| Hanriot, 'Comptes rendus de la Societe de biologic,' 1901, p. 70. 



f" See Lewkowitsch, 'Journal of Society of Chemical Industry,' 1903, vol. 22 

 No. 2. 



