!22 



INTRODUCTION OF THE FOOD. 



1. The introduction and mastication of the food; the movements of the tongue; 



insalivation ; formation of the bolus of food. 



2. Deglutition. 



3. The movements of the stomach, small and large intestine. 



4. The excretion of faecal matters. 



152. INTRODUCTION OF THE FOOD. Fluids are taken into the mouth in 

 three ways : (1) By suction, the lips are applied air-tight to the vessel containing 

 the fluid, while the tongue is retracted (the lower jaw being often depressed) and 



Fig. 162. 

 Soleil-Veutzke's polarisation apparatus. 



acts like the piston in a suction-pump, thus causing the fluid to enter the mouth. 

 Herz found that the negative pressure caused by an infant while sucking = 3 to 10 

 mm. Hg. (2) The fluid is lapped when it is brought into direct contact with the 

 lips, and is raised by aspiration and mixed with air so as to produce a characteristic 

 sound in the mouth. (3) Fluid may be poured into the mouth, and as a general 

 rule the lips are applied closely to the vessel containing the fluid. 



Solids, wheu they consist of small particles, are licked up with the lips, aided by 

 the movements of the tongue. In the case of large masses, a part is bitten off with 



