PANCREATIC DIGESTION. 161 



the pancreatic peptone is being produced, a further change occurs, 

 which gives rise to the formation of two crystallizable nitrogenous 

 bodies known as leucin and tyrosin, the former belonging to the 

 fatty acid, and the latter to the aromatic acid group. These 

 substances, which are commonly found together as a result of the 

 decomposition of peptones, seem inseparable from pancreatic di- 

 gestion, and increase in amount towards the later stages of the 

 action. 



The amount of peptone produced reaches a maximum in about 

 four hours, after which the proportion of the different unknown 

 decomposition products appears to increase at the expense of the 

 peptone. Among these substances must be named indol and 

 skatol, the materials from which the process of pancreatic diges- 

 tion derives its peculiar odor. 



This breaking up of the surplus proteid food into bodies which 

 cannot be of much utility in the economy, and which, as will 

 appear hereafter, are but a step in the direction of their elimina- 

 tion, is probably an important part of the pancreatic function, 

 as it relieves the economy of a surcharge of albuminous sub- 

 stances. 



Small quantities of phenol are also found in conjunction with 

 the above. 



II. Action on Fat. The action of the pancreatic juice on fats 

 is of two kinds. (I.) Saponification. By the action of a special 

 ferment (steapsin) the neutral fats are split up into glycerin and 

 their corresponding fatty acids. The acids thus formed readily 

 unite with the alkali present, and thus form soap. The chemis- 

 try of the change will be found at p. 71, and may be thus shortly 

 stated, taking olein as an example. Olein is a compound of 

 oleic acid and glycerin. Olein in presence of ferment and soda 

 gives glycerin and oleic acid, and the latter combines with soda 

 to form soap. This process materially aids in the next. (II.) 

 Emulsification. Which means that the fat is reduced to a state 

 of very fine subdivision, as it exists in milk. The production of 

 this condition is facilitated by (1), the quantity of albumin in 

 solution; (2), the alkalinity of the fluid; (3), the presence of 

 soap alluded to above ; and (4), the motion of the intestines. 



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