336 STUDIES IN ADVANCED PHYSIOLOGY. 



these envelopes and allow the contents to run together, a 

 result which is easily brought about by the mechanical 

 crushing- of these envelopes in the familiar process of 

 churning. It might, however, be brought about just as 

 easily by adding bits of pepsin and acid to the cream and 

 allowing this pepsin to digest away the albuminous cover- 

 ings, and so permit the buttery droplets to run together. 



Such a condition of things we meet with in the stomach. 

 Fats taken in the form of such droplets, as in milk or cream, 

 have their albuminous covering digested away by the gas- 

 tric juice, and the fatty contents liberated. Or when fatty 

 meat is taken, the connective tissue covering as well as the 

 coverings of the fatty cells are digested away and the con- 

 tained fat set free. But this action is clearly an action on 

 the albumens and albuminoids, and has really nothing to do 

 with the digestion of the fats themselves. 



Gastric juice will digest the albuminoids. Bits of white 

 fibrous tissue, or ordinary connective tissue or cartilage are 

 disintegrated and the gelatine extracted. 



SUMMARY. 



When the process of gastric digestion, after a period of 

 four or five hours comes to an end, we find the following 

 state of things: 



First. The change from the starch to the sugars begun 

 by the ptyalin in the mouth is temporarily arrested in the 

 acid juice of the stomach. 



Second. A large part of the proteids have been taken 

 through several intermediate stages and been finally changed 

 into dialyzable peptones. 



Third. Starches have in no wise been affected. 



Fourth. Pure fats have not been affected at all, but fats 

 when surrounded with albuminous envelopes, as in the case 

 of milk or cream, or of fat meat, have had these albumin- 

 ous coverings digested away, and been thus liberated. 



Fifth. Sugars have not been acted upon. 



