No. 3.] OESOPHAGEAL GLANDS OF URODELA. 97 



like that of the adult except in its great capacity for division. The 

 posterior portion 1.3 mm. in length is still quite devoid of glands. 



Staining with haemalum and neutral gentian shows that at 

 this stage also the cells forming the body of every gland in 

 the foregut contain both abundant zymogen granules and pro- 

 zymogen, and it is impossible to discern any difference what- 

 ever in the cells composing the large anterior flask-shaped 

 glands and the smaller posterior tubular glands respectively, 

 except that in the latter there is no evidence of distention and 

 consequent flattening. 



From this stage onward the changes proceed somewhat more 

 slowly and may be summed up briefly. 



In a larva 25 mm. in length the foregut measured 5.6 mm. 

 in length. Of this the anterior 1.4 mm. was non-glandular, 

 showing a relatively more rapid growth in length in this 

 portion of the foregut. The ciliated epithelium extended a 

 further distance of .84 mm. into the stomach, the posterior 

 portion of which, 3.36 mm. in length, was lined by the usual 

 mucigenous epithelium. 



Fig. 5 is from a larva 32 mm. in length. It is at this stage 

 that the resemblance to the oesophageal glands of Proteus and 

 Necturus is most marked. The duct of the gland and the por- 

 tion of the wall nearest 

 to the surface epithe- 

 lium are composed of 

 elongated cylindrical 

 cells forming a single 

 row. Four of these 



Cells are rCOresented in ^ IG ' 5-~ Larva f Amblystoma 32 mm. in length; oesophag- 

 eal gland. Ross obj., -fa in., Leitz ocular No. i. 



Fig. 6, A, as seen under 



a high magnification. Each presents an outer granular proto- 

 plasmic zone in which the oval nucleus is imbedded, and an 

 inner more extensive zone which is coarsely reticular. They 

 obviously represent the large, clear mucous cells of the ordi- 

 nary gastric glands, and, as we shall see, are actually transformed 

 into these in the adult. The difference in shape is dependent 

 on external conditions, such as the grouping of the cells, and 

 is not inherent in the cells themselves. 



