108 



This combination of the united pancreatic and biliary fluids poured on 

 the chyme, penetrates it, renders it fluid, anamalizes it, separates the 

 chylous from the excrementitious part, and precipitates whatever is no: 

 nutritious. In bringing about this separation, the bile itself seems to be 

 divided into two parts, its oily, coloured, and bitter portion passes along 

 Avith the excrements, sheathes them, and imparts to them the stimulating 

 qualities necessary to excite the action of the digestive tube. Its albu- 

 minous and saline particles combine with the chyle, become incorporated 

 lo it, are absorbed along with it, and return into the circulation. There 

 may, in fact, be noticed in the alimentary mass, after it has undergone 

 this combination, two very ^distinct parts, the one is a whitish milky sub- 

 stance, which swims to the surface, and is the least in quantity ? the 

 other is a yellowish pulp, in which, when digestion is healthy, it is not 

 easy to recognize the nature of the food. When the liver is obstructed, 

 and the bile does not flow in sufficient quantity, the faeces are dry and 

 discoloured; the patients are troubled with obstinate costiveness, the 

 excrement, uncombined with the bitte? and colouring matter of the bile, 

 not proving sufficiently irritating to the intestinal canal. 



We have just mentioned how the separationof the chyle is performed; 

 but the mechanism of that separation and the process of chylification are 

 absolutely unknown. How does the union of the bile to the chyme ope- 

 rate, in extracting- from the latter the recrementitious part, and in making 

 it swim above the rest? Is there any connexion between that process and 

 the nature of the constituent principles of the bile ? The knowledge of 

 the composition of the bile, affords as little assistance in the explanation 

 as does the knoAviedge of the chemical properties of the semen, in under- 

 standing the admirable function of generation. All these acts of the ani- 

 mal economy, are as mysterious and inexplicable, as the action of the 

 brain in producing thought, a phenomenon which so many physiologists 

 have considered as exceeding the power of matter, and for which they 

 seem to have reserved all th-oir admiration, though nil mirari, which I 

 would translate by wondering at nothing, ought to be the motto of any one 

 -who has made some progress in ti-e study of the laws of life. 



XXVIII. Of the action of the smalt Intestines. After remaining a certain 

 time within the duodenum, the alimentary mass decomposed by the bile, 

 or rather by the pancreatico-biliary fluid separated into two parts, the 

 one chylous, the other excrementitious, passes into the jejunum and 

 ileum, which are not easily distinguished from each other, and which dif- 

 fer in their relative length, according to the elements on which anato- 

 mists ground the distinction*. 



* The redness of the parietes of the jejunum, the empty condition of that intestine, 

 its situation in the umblical region, the great number of its valvulze conniventea, do not 

 distinguish it from the ileum, for, the colour of the intestinal canal varies in different 

 parts (/fits extent, and the substances which fill it are found in different parts of the 

 canal, according to the progress of digestion at the time the parts are examined ; ac- 

 cordin ' as the convolutions are situated within the cavity of the pelvis, or rise towards* 

 the epigastric region ; according to the full or empty state of the bladder and stomach - r 

 and the number of circular folds, called valvulse conniventes, diminishes, as on-e gets- 

 near to the termination of the ileum. Winslow got over the difficulty, by considering; 

 tile upper two-fifths of the small intestines as jejunum, and the remaining three-fifths 

 as ileum. This last division, from measurement, is wholly arbitrary, and is besides 

 useless, for there is not, perhaps, above one occasion in which it would be interesting 

 to distinguish the jejunum from the ileum. In operating for hernia, when the intes- 



