and the Action of the Bile in Digestion. 309 



returns to its former condition, the drop of oil will also assume 

 its original shape. 



6. The Influence of Bile. 



For the bile that I employed in my experiments I am in- 

 debted to the kindness of my colleague W. Kiihne ; it was 

 prepared by evaporating to dryness over the water-bath an 

 alcoholic solution of crystallized ox-gall, and dissolving the 

 residue in water. 



If some solution of bile be added to the fluid in which floats 

 a drop of olive, almond, or cod-liver oil coated with a solid 

 soap membrane, this membrane will be dissolved ; the oil-drop 

 assumes the spherical form, and retains it after agitation. On 

 this ability of bile to transform a solid into a fluid soap, or into 

 a soap-solution, seems to depend its property of promoting the 

 assimilation of fat in the animal body. Solid particles of soap 

 on the surface of an oil-drop prevent any change of form in 

 that surface, and thus diminish its ability to pass through ani- 

 mal membranes. This hindrance is removed so soon as the 

 drop is coated with a fluid membrane. Bile has the property 

 of promoting the spontaneous formation of an emulsion when 

 the solid soap at the common surface of the oil and the soda- 

 solution dissolves slowly ; but it counteracts the emulsion-for- 

 mation when it converts the solid soap into a liquid too rapidly. 

 Both of those phenomena were observed by Gad. 



According to the views of C. A. von Wistingshausen *, 

 the bile, drawn through the walls of the lacteals, is accom- 

 panied by the adhering particles of fatty matter ; but, as it 

 seems to me, this theory has not up to the present been 

 proved. The same observer claims to have found that olive- 

 oil will rise higher in capillary tubes moistened with various 

 liquids when those liquids contain in solution salts of the 

 biliary acids. For moistening the tubes, water and dilute solu- 

 tion of potash were used, with or without the addition of 

 albumen. 



Unfortunately we are unable to gather from the descriptions 

 of these experiments in what way the capillary glass tubes were 

 moistened with the liquid. If the oil in rising drives before it a 

 continuous layer or column of the liquid, my own experience is, 

 contrary to that of von Wistingshausen, that oil will rise higher 

 in capillary tubes wetted with water than in those moistened 

 with solutions of bile of different degrees of concentration. In 

 the presence of potash it may behave differently ; the solid soap 



* Compare J. Steiner on C. A. von Wistingshau sen's " Researches on the 

 Action of the Bile in the Absorption by Endosrnose of the Neutral Fats," 

 Du Bois-Eeymond's Archiv, 1873, p. 139. 



