160 THE BIOLOGY OF THE ANIMAL 



stomach are hard and firm, while others are more 

 flexible. What relation exists between the mus- 

 cles and the hardened portions of the stomach 

 wall? Carefully remove the stomach from the 

 surrounding parts, cutting ofE the entrance, or 

 oesophagus, close to the mouth, and leaving 

 about an inch of the intestine attached. What 

 is the position of the stomach with regard to the 

 mouth ? Lay the stomach on its side in a dish of 

 water or fifty per cent, alcohol, and remove all 

 of the superfiuous parts. Do you find that the 

 wall consists of two layers ? To which of these 

 are the muscles attached? In which do the 

 hardened portions lie ? Does the outer fit closely 

 over the inner coat? What is the shape of the 

 stomach when seen sidewise? Draw. Examine 

 the oesophagus or gullet. How long is it ? How 

 wide ? Are its walls flexible or rigid ? At what 

 point does it enter the stomach ? Can it be di- 

 lated ? Is its lining continuous with the outer 

 covering of the body ? Note the two regions of 

 the stomach proper, the anterior or cardiac re- 

 gion and the posterior or pyloric region. How 

 do they compare in size ? If collapsed, the stom- 

 ach may be distended by injecting water into the 

 oesophagus. What difference in shape ? 



JSTote the lining of the stomach. Of what is it 

 composed? Trace it to the mouth. Remove a 

 portion of the roof and front wall of the stomach, 

 so as to expose the interior, being careful not to 

 cut away any of the hardened portions or ossi- 

 cles. Examine the ossicles and try to malse out 

 the following, studying in each case the position, 

 shape, size, and attachments : 



