XXI] (ESOPHAGUS AND STOMACH 169 



The submucous tissue may contain one or two small 

 serous and mucous glands (cp. Lesson XX.). Each 

 of these consists of a duct, dividing and ending in 

 dilatations, the alveoli. 



The muscularis mucosse, internal to (i.e. on the 

 epithelial side of) the alveoli of the glands. 



The papillae of the mucous membrane. 



The stratified epithelium forming a layer several 

 cells deep, the deeper being columnar or spheroidal, 

 the superficial cells flattened (cp. Epidermis, Lesson 



XXVII.). 



NOTES. 



Hardening. The stomach should be taken immediately after 

 death, cut open and the mucous membrane washed in salt solution ; 

 the wall, or the mucous membrane only, is pinned out on cork and 

 placed in alcohol or other hardening agent. Or the stomach may be 

 washed out from the oesophagus, and then moderately distended with 

 alcohol. 



Osmic acid is excellent for lower vertebrates, but it does not as a 

 rule preserve the cell granules in mammals ; it does however in the 

 bat, and sometimes in the mole. 



Gastric glands of newt with blood circulating round them. The 

 brain is destroyed ; the newt is pinned on its back on the stage, the 

 abdomen just below the fore limb and on the left side being opposite 

 the hole in the stage; the hole in the stage should be about 1 to 

 1J cm. long and -5 to '75 cm. broad, the cork or india-rubber 

 surrounding the hole being 2 to 3 mm. high. A lateral cut is made 

 through the abdominal skin, the stomach drawn out; this is cut open 

 2 to 3 mm. from the mesenteric attachment on the lower side ; the 

 wall is then pinned out with hedgehog quills, the muscular coat being 

 uppermost this is best done under a low power to see that no tension 

 is applied to the veins (cp. also Less. xvn. 9). A portion of the 

 muscular wall may be cut away. 



The cardiac glands of the newt appear as small round granular 



