TRANSFERENCE OF FOOD MATERIALS 115 



to the various food substances. Where the gland is situated 

 away from the surface of the alimentary canal and is connected 

 with the surface by a definite tube or duct, the secretion may 

 be collected before it is mixed with the food materials. Owing 



APPENDIX 



FIG. 23. Diagram showing the general arrangement of the Alimentary 



Canal. 



The salivary glands open into the mouth by ducts, one pair opening at the side of the cheek 

 above the tongue, and two pairs below the tip of the tongue. Where the duodenum turns 

 sharply beyond the stomach the entrance of the pancreatic duct and bile duct is seen : con- 

 nected with the latter is the gall bladder, which stores the bile between its periodic discharges 

 into the intestine. After the duodenum is seen the jejunum (J) and ileum (I) which form 

 the rest of the small intestine. 



The large intestine is composed of appendix, caecum (G), transverse colon (T), sigmoid 

 colon (S), and rectum (R). 



(Redrawn from " Elementary Physiology." Huxley. Macmillan). 



to the presence of definite glands and ducts the processes 

 of solution by the enzymes are more easily studied in ani- 

 mals than in plants where the enzymes are not so definitely 

 separated from the food supplies. 



