Digestion The Stomach 111 



which animals are liable to swallow, such as small 

 stones, pins and nails. The contents of this compart- 

 ment of the stomach are very watery, a condition which 

 is said to aid the return of the food to the mouth, por- 

 tion by portion, for remastication. 



Rumination, which is the re -chewing of food pre- 

 viously swallowed, is peculiar to bovines, sheep and 

 goats. In the case of these species, the mastication of 

 coarse fodder is not completed before it is swallowed 

 the first time, and they have the power of returning to 

 the mouth the material which has become stored in the 

 paunch and honeycomb in order that it may be more 

 finely ground. This is what is termed "chewing the 

 cud." It is an operation which greatly aids digestion 

 by rendering the food mass finer and more susceptible 

 to the action of the digestive fluids. Animals fed on 

 grain alone do not ruminate. They "lose their cud," 

 a condition popularly and erroneously supposed to be 

 fatal to the animal's life. 



After remastication, the food does not return wholly 

 to the first and second stomachs, but is mostly carried 

 along in what is known as the cesophagal groove to the 

 third stomach, the omasum. The finer portions may 

 even do this when first swallowed. The many -plies 

 (omasum) is a cavity somewhat larger than the honey- 

 comb, which has a most curious interior structure. It 

 is filled with extensions of the mucous membrane in 

 the form of leaves, between which the food passes in 

 thin sheets, an arrangement which seems to have for 

 its purpose the further grinding of the food so that 

 when it finally reaches the fourth and last compart- 



