MOVEMENTS OF THE ALIMENTARY CANAL. 719 



the fundic end may remain undisturbed for a long time and thus 

 escape mixture with the acid gastric juice, so far at least as the 

 interior of the mass is concerned. 

 This fact is of importance in con- 

 nection with the salivary digestion 

 of the starchy foods. Obviously, 

 salivary digestion may proceed for 

 a time in the fundic end without 

 being affected by the acid of the 

 stomach. Griitzner fed rats with 

 food of different colors and found 

 that the successive portions were 

 arranged in definite strata. The .r..^ J^^^ a£,^^ 

 food first taken lay next to the s^ow the stratification of food given 



-^ 1 ., 1 ** different times.— (Grutzner.) The 



walls OI the stomach, while the ^ooJ was sdven in three portions and 



,. ,. , colored differently: first, black; sec- 



SUCCeedmg portions were arranged ond, white (indicated by vertical 



11 • ,1 • J. • • marking); third, rea (indicated hv 



regularly m the interior m a con- transverse marking). 

 centric fashion, as shown in the 



figure. Such an arrangement of the food is more readily understood 

 when one recalls that the stomach has never any empty space 

 within; its cavity is only as large as its contents, so that the 

 first portion of food eaten entirely fills it and successive por- 

 tions find the wall layer occupied and are therefore received 

 into the interior. Cannon* has reported some interesting experi- 

 ments upon the relative duration of gastric digestion for carbo- 

 hydrates, proteins, and fats when fed separately and combined. 

 The foods were mixed with subnitrate of bismuth and their 

 position in the stomach and passage into the intestine were 

 watched by means of the Roentgen rays. It was found that 

 carbohydrate food begins to pass out from the stomach soon after 

 ingestion, and requires only about one-half as much time as the pro- 

 teins for complete gastric digestion. Fats remain long in the 

 stomach when taken alone, and when combined with the other 

 foodstuffs markedly delay their exit through the pylorus. This 

 distinct difference in the main foodstuffs can hardly be referred to 

 mere mechanical consistency, since the fats are liquefied by the 

 heat of the body. Cannon has shown that this regulation is not 

 effected through the agency of the extrinsic nerves. After section of 

 the splanchnics and vagi the difference in time between the ejection 

 of carbohydrate and protein material still exists, so that the con- 

 trol in this matter must be exerted through some local mechanism 

 in the stomach itself. If, in a given diet, the carbohydrate is fed 



* Cannon, "American Journal of Physiology," 12, 387, 1904. For a 

 general review of Cannon's work, see "American Journal of the Medical 

 Sciences," April, 1906. 



