Digestive Functions 255 



Neilson, Lewis and Terry (1906, 1908) found the amylolytic power 

 of human saliva to increase markedly when the diet was rich in 

 carbohydrate; they even reported similar observations in dogs. 

 Mendel and Underhill (1907) were unable to reproduce these find- 

 ings on dogs; Samytschkina (1932), however, noticed amylase 

 activity in saliva of dogs fed for some days on a carbohydrate diet. 

 Further experiments in this field seem desirable. 



The fact that the food remains in the mouth for a short period 

 only, might seem to reduce the importance of the salivary amylase. 

 As is well known, however, the splitting of polysaccharides under 

 the influence of saliva continues in the stomach. The fundamental 

 experiments by Cannon (1898) in which the alimentary canal was 

 made visible on the x-ray screen by means of a bismuth prepara- 

 tion, revealed that the fundus of the stomach is relatively quiescent, 

 whereas the pyloric region is active. Cannon concluded "that the 

 fundus acts as a reservoir for the food, in which the digestion of 

 sugars and starches may take place". That the contents of the 

 fundus is only slowly mixed with acid gastric juice was proved in 

 the following experiment: "A cat which had been without food for 

 fifteen hours was given eighteen grams of mushy bread made 

 slightly alkaline with sodium carbonate. One hour and a half after 

 the cat had finished eating, she was killed and the stomach laid 

 bare by opening the abdomen. A very small hole was then made 

 through the wall in the fundus region, and another similar hole was 

 made into the antrum. By means of a glass pipette food was ex- 

 tracted first from the periphery of the fundus ; this food was slightly 

 acid. The cleaned pipette was then introduced two and a half 

 centimetres into the fundus contents and the food thus extracted 

 gave the original alkaline reaction. Specimens of the liquid con- 

 tents of the antral and middle regions, taken from various depths, 

 were all strongly acid." 



Gmtzner (1905) fed rats on three successive portions of bread 

 differently coloured; the animals were then killed, the stomachs 

 extirpated, frozen and cut through. The different portions of food 

 could be distinctly separated from each other, the food given last 

 being close to the oesophagus and surrounded by the second por- 

 tion; the first portion was nearest to the wall of the stomach. 

 Enzymatic studies showed that an amylolytic activity could exist 

 in the part of the stomach near the oesophagus simultaneously 

 with a peptic activity in the pyloric region. This fact has been 



