306 THE DIGESTIVE ACTIVITY OF THE PANCREATIC JUICE. 



result also in the germination of certain plants, by reason of which there is a 

 resemblance between the transformation and the consumption of nutritive mate- 

 rials in seeds and the digestive effects of ferments. 



The lipolytic activity depends on the presence of a ferment termed 

 steapsin or pialyn, which exerts its action more especially on the neutral 

 fats. This action is two-fold: (i) they are transformed into a fine, 

 permanent emulsion, and (2), by taking up water, they undergo a cleav- 

 age into glycerin and fatty acids. 



C57H 110 0. + 3 H 2 = C 3 H 8 3 + 3(CH,A) 



Tristearin + Water = Glycerin + Stearic Acid. 



The addition of bile increases this action in the rabbit very consid- 

 erably. This cleavage action is due to a ferment, especially decomposed 

 by acids, but which has not yet been isolated. Lecithin is split up by 

 this ferment into glycerinphosphoric acid, neurin and fatty acids. 



After decomposition is complete, the fatty acids are in part united 

 with the alkalies of the pancreatic juice and the intestinal fluid to form 

 fatty-acid alkalies, or soaps; and in part emulsified in the alkaline in- 

 testinal juice. Both the emulsion and the soap-solution are capable of 

 being absorbed. After extirpation of the pancreas in the dog, the 

 digestion and absorption of fats are correspondingly diminished. 



If the fat to be emulsified contains free fatty acids, as is the case with all 

 of the fats of the food, and if the fluid at the same time has an alkaline reaction, 

 emulsification takes place with extraordinary rapidity. A drop of cod-liver oil, 

 which likewise always contains some free acid, placed in a 0.3 per cent, soda-solu- 

 tion, is at once broken up into fine emulsion-granules. First a hard soapy mem- 

 brane is formed on the surface of the oil-drop; this, however, is quickly dissolved 

 and small drops are thereby torn away. The fresh surface becomes again covered 

 with a layer of soap and the process is continually repeated. The soaps produced 

 themselves in turn act as emulsifiers. If the amount of oleic acid contained in 

 the oil and the concentration of the soda-solution are increased, so-called "myelin- 

 forms" are produced, that is, forms like those that appear when fresh nerve-fibers 

 are teased in aqueous liquids. Animal fats furnish an emulsion more readily than 

 vegetable fats, castor-oil not furnishing any at all. 



The fatty acids also may undergo still further decomposition through the action 

 of the fat-splitting ferment, with the production of carbon dioxid and hydrogen 

 even, in the absence of microorganisms. 



Danilewsky isolated the four pancreatic ferments in the following manner: If 

 an acid infusion of dog's pancreas is super-saturated with magnesium oxid, the 

 precipitate carries the fat-ferment down with it. Collodion added to the filtrate 

 precipitates the trypsin; the precipitate is collected; and the collodion is dissolved 

 out by a mixture of ether and alcohol. The diastatic ferment is contained in the 

 filtrate from the collodion-precipitate. 



For testing the digestive activity of the pancreas an extract of the swollen 

 and reddened gland may be prepared after trituration with the aid of concentrated 

 solution of sodium chlorid. Triturated pancreas, which has lain for a day, can 

 also be extracted with glycerin or chloroform-water. Alcohol precipitates the fer- 

 ments in these extraction-fluids. Kuhne renders the minced pancreas free from 

 water and fat by means of alcohol and ether, and pulverizes it. The powder, to 

 which 10 parts of o.i per cent, salicylic acid solution at blood-heat are added, 

 exhibits the activity of the ferments. An extract of the pancreas, prepared rapidly 

 and at a high temperature with a 0.7 per cent, solution of sodium chlorid, contains 

 almost alone the sugar-forming ferment, which is absent from the gland in the 

 state of hunger. After long-continued maceration at a later period trypsin prin- 

 cipally is obtained. 



To demonstrate the effects of the pancreas Setschenow proceeds as follows: 

 Minced calf's pancreas is infused with less than double its volume of water and 

 is kept at a temperature of 38 C. for five hours. The decanted fluid is strained, 

 shaken with ether, and alcohol is added until a precipitate forms. The latter is 

 spread uniformly upon filter-paper by filtration, and the paper is dried at a tern- 



