324 PHYSIOLOGY AND MORPHOLOGY OF ANIMALS. 



(b) The pancreas (sweetbread') lies just below the 

 stomach, and its excretory duct unites with the bile duct 

 to open by a common duct into the duodenum. Its 

 structure is similar to that already described in the sali- 

 vary gland. Its secretion is perhaps the most impor- 

 tant of all the digestive juices. It performs the func- 

 tion of all previously mentioned, and supplements them 

 all. It saccharizes starch, like the saliva. It peptonizes 

 albuminoids, like the gastric juice. It is slightly alka- 

 line, like the bile, and it is a powerful emulsifier of fat, 

 like the intestinal mucus. These properties are the 

 result of several ferments, among which may be men- 

 tioned pancreatin or amylopsin and trypsin, the former a 

 solvent of starch and the latter of albuminoids. What- 

 ever of albuminoids or amyloids escape digestion in the 

 stomach are dissolved here.* It also forms still another 

 ferment which splits fats into glycerin and fatty acids. f 

 In addition to all these the pancreas has still other 

 functions, which will be discussed later. Suffice it to 

 say now that it apparently delivers a peculiar ferment 

 directly to the blood. 



(c) The intestinal secretion probably has other diges- 

 tive properties little known, but certainly by its slimy 

 viscidity it is very efficient in the emulsification of fats. 



Emulsion. — We have said that chyle is a milky 

 liquid. Its whiteness is wholly due to emulsified fats. 

 We explain this as follows: Ice is transparent, but break 

 it up into fine particles like snow and it is intensely 

 white.- Glass is transparent, but grind it to fine powder 

 and it is white. Water is transparent, but spray and 

 foam are white. And so in all cases of whiteness. Oils 



* Recently shown (Archives des Sciences, iv, 490, 1897) that the 

 spleen furnishes a product necessary to the formation of trypsin, 

 f Am. Nat. xxxi, 1040, 1897. 



