MULTICELLULAR ANIMALS 



i6i 



muscles and increasing peristalsis. Hunger distress appears to be 

 caused by contractions of the walls of the stomach; it has been 

 found that hunger pangs are relieved if the stomach is distended 



TONGUE 



OESOPHAGUS 



GALL BLADDER 



LIVER 



DUODENUM 



ASCENDING COLON 



CAECUM 



VERMIFORM APPENDIX 



ORAL CAVITV 

 PHARYNX 



STOMACH 



PANCREAS 



TRANSVERSE COLON 



JEJUNUM 



ILEUM 

 DESCENDING COLON 



RECTUM 



Fig. io8. — The human digestive system in diagram. The liver has been pulled 

 aside to show the position of the gall bladder and of the bile duct. (Partly after 

 Sobotta: Atlas and Textbooli of Human Anatomy, published by \V. B. Saunders Co.) 



mechanically, for instance by the inflation of a rubber balloon that 

 has been swallowed. 



Digestion in the Mouth. Chemical changes in the food be- 

 gin in the mouth. There the diastase, ptyalin, in the neutral or 



