The Digestive System 133 



luated appearance. In this compartment, the softened grasses are formed 

 into cuds which are regurgitated into the mouth for further mastication. 

 After a prolonged chewing, the food is reswallowed and enters into 

 the omasum and ahomasum where chemical digestion is continued. 



The camel, which is also a ruminant, has a further use for its 

 reticulum. It acts as a reservoir for water, allowing the camel to sur- 

 vive long periods without drinking. 



PYLORUS 



GBEATEB 



CURVATURE 



Fig. 41. — Mammalian stomachs. A, The cow; B, man. 



The vampire bat also has an interesting modification in its stomach. 

 A portion of the fundus forms an elastic pouch in which blood is stored 

 after the bat has feasted. 



The stomach of birds has the cardiac and pyloric sections com- 

 pletely separated. The cardiac portion is the glandular portion where 

 food is prepared for further digestion. The pyloric portion becomes 

 the gizzard which has a heavy muscular wall. Here the food is ground 

 up. Small stones which the birds swallow act as grinding surfaces. 

 As birds have no teeth, these stones perform an essential service. 



