CHEMICAL PHYSIOLOGY. 11 



somewhat turbid matters, to which the name of 

 peptones is given. Pepsine may be isolated by me- Peptone 

 chanical precipitation in the same manner as ptyaline 

 by adhesion to phosphate of lime. It is not itself 

 destroyed during digestion, but is capable of trans- 

 forming great quantities of solids into fluid by that 

 mysterious influence termed contact action. When 

 the juice is saturated with peptones it ceases to act, 

 but an addition of dilute acid fluid enables digestion of 

 newly introduced albuminous matters to be effected. 

 The secretion of the hydrochloric (and lactic ?) acid 

 from the stomach glands is a chemolytic process by 

 which salts of alkalies are split up into acid and 

 base. Of this action I shall show the completion 

 of the circle in the biliary function immediately to 

 be described. The origin of the pepsine is the blood, 

 but which ingredient of this fluid yields this curious 

 substance, which is so different from albumen, cannot 

 be told. In the stomach digestion saliva by its ptyaline 

 forms some sugar, the gastric juice fluidifies the albu- 

 minous matters, the fats are made fluid and liberated 

 from their tissue connections, vegetable structures are 

 variously disintegrated, and the whole is mixed with 

 water and a small amount of air carried down in 

 the process of swallowing. Other decompositions, as 

 yet imperfectly understood, also take place, as evi- 

 denced by the strong odour of the digested matters, and 

 at last the homogeneous mixture of substances, termed 

 chyme, passes through the pylorus into the duodenum. 



The ingredients of chyme are starch, sugar, fat, chyme. 

 and peptones, or if only animal food had been eaten, fat Peptones 



