74 



MARY 



ROSS. 



going on the insinkings at the surface (Figs. 3, 10, d] continue 

 to deepen, forming, in Desmognathus, narrow tubes. The gland 

 fundament, by rapidly increasing in size, is forcing its way, not 

 down into the mesodermic layer, though there is a slight burrow- 

 ing in this direction (Figs. I, 3, a), but toward the lumen of the 

 stomach. The epithelial cells of the surface are being pushed out 

 of their original position, and arranged around the gland funda- 

 ment as a central axis (Figs. 3, 4, cp). As the free surfaces of 



FIG. 8-1 1 represent a series of sections through a gland of the pyloric region of 

 the stomach of a 16 mm. larva. Fixed in Gilson's. Letters as in Fig. I. Obj. T ^, 

 Oc. I. 



FlG. 8. flj, transection through a gland fundament showing the lumen ; </., the 

 insinking at the surface is more marked than in earlier stages ; n., cells which later 

 take part in forming the neck. 



the cells are thus withdrawn from facing the cavity of the stomach 

 to form the lumen of the gland, or, speaking more accurately, to 

 form the excretory duct, the epithelial cells adjoining the gland 

 proper, or fundus, become rounder and appear in a more active 

 condition than the rest of the epithelium. This is shown in Figs. 



