FANCKEATIC JUICE, AND THE DIGESTION OF FAT. 153 



into the abdomen, and the external wound closed by sutures. 

 After six or eight hours the animal is killed, and the fluid, which 

 has collected in the isolated portion of intestine, taken out and 

 examined. The above was the method adopted by Frerichs. Bid- 

 der and Schmidt, in order to obtain pure intestinal juice, first tied 

 the biliary and pancreatic ducts, so that both the bile and the pan-, 

 creatic juice should be shut out from the intestine, and then estab- 

 lished an intestinal fistula below, from which they extracted the 

 fluids which accumulated in the cavity of the gut. From the great 

 abundance of the follicles of Lieberkuhn, we should expect to find 

 the intestinal juice secreted in large quantity. It appears, however, 

 in point of fact, to be quite scanty, as the quantity collected in the 

 above manner by experimenters has rarely been sufficient for a 

 thorough examination of its properties. It seems to resemble very 

 closely, in its physical characters, the secretion of the mucous folli- 

 cles of the mouth. It is colorless and glassy in appearance, viscid 

 and mucous in consistency, and has a distinct alkaline reaction. 

 It has the property when pure, as well as when mixed with other 

 secretions, of rapidly converting starch into sugar, at the tempera- 

 ture of the living body. 



PANCREATIC JUICE. AXD THE DIGESTION OF FAT. The only re- 

 maining ingredients of the food that require digestion are the _oily 

 matters. These are not affected, as we have already stated, by con- 

 tact with the gastric juice ; and examination shows, furthermore, 

 that they are not digested in the stomach. So long as they remain 

 in the cavity of this organ they are unchanged in their essential 

 properties. They are merely melted by the warmth of the stomach, 

 and set free by the solution of the vesicles, fibres, or capillary tubes 

 in which they are contained, or among which they are entangled ; 

 and are still readily discernible by the eye, floating in larger or 

 smaller drops on the surface of the semi-fluid alimentary mass. 

 Very soon, however, after its entrance into the intestine, the oily 

 portion of the food loses its characteristic appearance, and is con- 

 verted into a white, opaque emulsion, which is gradually absorbed. 

 This emulsion is termed the chyle, and is always found in the small 

 intestine during the digestion of fat, entangled among the yalvulse 

 conniventes, and adhering to the surface of the villi. The digestion 

 of the oil, however, and its conversion into chyle, does not take 

 place at once upon its entrance into the duodenum, but only after 

 it has passed the orifices of the pancreatic and biliary ducts. Since 



