THE ORIGIN AND DEVELOPMENT OF GASTRIC GLANDS. 83 



stage there takes place a rapid disappearance of yolk, a rapid 

 multiplication of cells and a correspondingly rapid insinking of 

 the surface epithelium to form the excretory duct. At the time 

 of hatching there is, as before described for Desmognathus, a 

 union of the gland fundus with the excretory duct, the cells show- 

 ing marked mitoses at this point (Fig. 23, ;/). 



There are several points in which the Amblystoma appears to 

 differ from the Desmognathus, The cells of the surface epithelium 



d. 



. * .,,.. 



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FIG. 20. Same as Fig. 18. Larva 13 mm. a., groups of cells, two, three and 

 four, by increasing in size, are pushing the epithelial cells aside. Thus the indenta- 

 tion, d, is being deepened. The yolk is also being absorbed, making the epithelium, 

 ep., narrower or lower. Obj. j 1 ,-,, Oc. 2. 



are fewer in number, being distended with yolk. The excretory 

 duct is shorter, the glands opening on the surface of the stomach 

 by very short necks. As the yolk is absorbed the columnar 

 epithelium lining'the stomach becomes lower; the gland funda- 

 ments increase more rapidly than the surface epithelium, as the 



