CHEMICAL PHYSIOLOGY. 13 



During digestion some gases, consisting of carbonic Gases. 

 acid, hydrogen, and nitrogen, are not rarely formed 

 from the digesting food. This may become a dis- 

 tressing symptom in disease. 



Duodenal digestion is a continuation of stomach 

 digestion under greatly complicated circumstances, 

 since the chyme receives additions of bile and pancreatic 

 juice. The physiology of these liquids has been studied 

 upon fistulous openings occurring accidentally in man, 

 or produced by art in animals. The secretory acts 

 and influences are no doubt well known, particularly 

 their variations under several conditions. But the 

 employment of the secreted matters is by no means so 

 elucidated as to be capable of satisfactory theoretical 

 representation. The pancreatic juice has probably 

 three functions, of which one is the completion of the 6 func " 

 solution of the pieces of meat and albumen which 

 issue from the stomach with the chyme ; another is 

 the decomposition of fat into glycerine and fatty acid ; 

 and a third the emulging of neutral fat, and the trans- 

 forming of it into a subdivided condition, in which it 

 may pass through the pores of the mucous membrane 

 into the chyle-ducts. It also transforms a small 

 quantity of starch into sugar. These properties are only 

 possessed entire by juice which is abstracted from the 

 pancreatic duct of an animal during full digestion, or 

 from a reddened pancreas. Juice thus procured is 

 tough or viscid, and contains 10 to 11 per cent, of 

 solids, while juice obtained from a permanent fistula 

 has only 5 per cent, of solids, and lacks the power 

 of digesting albuminous fragments. It is probable that 



