82 NUTRITION OF FARM ANIMALS 



portion of the drink as reaches this stomach and is thoroughly 

 softened and prepared for further action. The rumen is 

 so large that it always contains a considerable amount of 

 material and the new feed when swallowed is more or less 

 completely mixed with that already in the rumen by the peri- 

 staltic action of the latter, thus tending to prolong its stay. 

 The liquid or finely comminuted portions probably pass on 

 directly to the omasum, or manifolds, and the abomasum, but 

 the bulk of the feed undergoes the process of rumination. 



After the animal has completed feeding, and if it is left in 

 quiet, small portions of the feed are raised again to the mouth 

 from the rumen and reticulum by contraction of these organs, 

 aided by the action of the abdominal muscles and of the dia- 

 phragm, thoroughly chewed and swallowed a second time. 

 This time they pass to a considerable extent, though not 

 entirely, the esophageal . canal and enter the third stomach, 

 the manifolds, and from this pass into the fourth or true 

 stomach. 



The ruminants are animals which in the wild state depend 

 on speed and cunning to escape from their enemies. Hence 

 it is an advantage to them to be able to consume hastily large 

 amounts of feed and then to retire to some safe concealment 

 to remasticate and prepare it for digestion. Rumination 

 also enables these animals to utilize more thoroughly coarse 

 rough fodders, the long stay in the paunch softening and fer- 

 menting the material and helping especially to destroy or dis- 

 solve the carbohydrates of the cell walls and thus render the 

 cell contents accessible to the digestive fluids. 



118. The gastric juice. The mucous membrane lining the 

 true stomach contains numerous simple glands (tubular glands) 

 differing in appearance in different portions of the stomach. 

 Those of the fundus region contain two kinds of secreting cells, 

 commonly designated as " chief " and " parietal " cells. The 

 glands of the pyloric end contain " chief " cells similar to those 

 of the fundus glands, but only an occasional " parietal " 

 cell. The parietal cells secrete as their essential product 

 hydrochloric acid. The " chief " cells produce the enzym 

 pepsin, or rather a precursor of pepsin called pepsinogen. 

 The mixed secretion of these different glands constitutes the 

 gastric juice, which is a thin, clear acid liquid having a 



