140 



THE BIOLOGY OF THE FROG 



CHAP. 



more or less branched. The glands differ in structure at 

 the two ends of the stomach. In the cardiac region the 

 glands are very long, the mouth of the gland is quite deep, 

 and lined with elongated cells whose clear inner ends 

 are filled with a substance which probably forms mucus. 

 Near the outer end of the gland the cells are more elongated, 

 like those of the surface epithelium : behind the clear sub- 

 stance the cytoplasm of the cells is granular, the nucleus is 



FlG. 39. Glands of the stomach. A, from cardiac end; B, from pyloric 

 end; m, mouth; n, neck; b, body ol gland. 



elongated, and the outer ends are drawn out into a long 

 narrow process. Passing down the mouth of the gland the 

 cells become shorter, the nuclei more rounded, and the tail- 

 )ike processes finally almost disappear. In the neck regions 

 of the gland there are usually a few rather large cells con- 

 taining a large clear vacuole which pushes the nucleus and 

 most of the cytoplasm to one side. It is usually in the 

 region of these clear cells that the glands branch. The cells 

 composing the body of the gland lie just below the clear 



