246 HANDBOOK OF PHYSIOLOGY. 



Honeycomb stomach, so called from the fact that its mucous membrane 

 is disposed in a number of folds inclosing hexagonal cells. 3. The 

 Psaltenum, or Manyplies, in which the mucous membrane is arranged 

 in very prominent longitudinal folds. 4. Abomasum, Reed, or Rennet, 

 narrow and elongated, its mucous membrane being much more highly 

 vascular than that of the other divisions. In the process of rumination 

 small portions of the contents of the rumen and reticulum are succes- 

 sively regurgitated into the mouth, and there thoroughly masticated and 

 insalivated (chewing the cud): they are then again swallowed, being this 

 time directed by a groove (which in the figure is seen running from the 

 lower end of the oesophagus) into the manyplies, and thence into the 

 abomasum. It will thus be seen that the first two stomachs (paunch and 

 reticulum) have chiefly the mechanical functions of storing and moisten- 

 ing the fodder: the third (manyplies) probably acts as a strainer, only 

 allowing the finely divided portions of food to pass on into the fourth 

 stomach, where the gastric juice is secreted and the process of digestion 

 carried on. The mucous membrane of the first three stomachs is 

 lowly vascular, while that of the fourth is pulpy, glandular, and highly 

 vascular. 



In some other animals, as the pig, a similar distinction obtains be- 

 tween the mucous membrane in different parts of the stomach. 



In the pig the glands in the cardiac end are few and small, while to- 

 wards the pylorus they are abundant and large. 



A similar division of the stomach into a cardiac (receptive) and a 

 pyloric (digestive) part, foreshadowing the complex stomach of rumi- 

 nants, is seen in the common rat, in which these two divisions of the 

 stomach are distinguished, not only by the characters of their lining 

 membrane, but also by a well-marked constriction. 



In birds the function of mastication is performed by the stomach 

 (gizzard) which in granivorous orders, e.g., the common fowl, possesses 

 very powerful muscular walls and a dense horny epithelium. 



Structure. The stomach is composed of four coats, called respec- 

 tively an external or (1) peritoneal, (2) muscular, (3) submucous, and 

 (4) mucous coat ; with blood-vessels, lymphatics, and nerves distributed 

 in and between them. 



(1) The peritoneal coat has the structure of serous membranes in 

 general. (2) The muscular coat consists of three separate layers or sets of 

 fibres, which, according to their several directions, are named the longi- 

 tudinal, circular, and oblique. The longitudinal set are the most superfi- 

 cial : they are continuous with the longitudinal fibres of the oesophagus, 

 and spread out in a diverging manner over the cardiac end and sides of 

 the stomach. They extend as far as the pylorus, being especially dis- 

 tinct at the lesser or upper curvature of the stomach, along which they 

 pass in several strong bands. The next set are the circular or transverse 

 fibres, which more or less completely encircle all parts of the stomach ; 

 they are most abundant at the middle and in the pyloric portion of the 

 organ, and form the chief part of the thick projecting ring of the py- 

 lorus. These fibres are not simple circles, but form double or figure- 



