No. 3-J OESOPHAGEAL GLANDS OF URODELA. 91 



of small size. For this purpose the writer employed Reinke's 

 neutral gentian as follows : To a saturated solution of gen- 

 tian violet in water a solution of orange G is added in excess. 

 A brownish precipitate is formed which is very slightly soluble 

 in water. This may be collected on a filter and washed until 

 the wash water is only slightly tinged. The precipitate is 

 then dissolved in alcohol. For use a sufficient quantity is 

 added to twenty per cent alcohol to make a fluid of about the 

 same color as a good solution of haemalum. Sections fastened 

 to the slide are stained in this for twenty-four hours, all adher- 

 ent stain is then removed by pressing clown upon the sections 

 several folds of filter paper, absolute alcohol added and quickly 

 removed with the blotter, and finally oil of cloves added in 

 which the differentiation of the stain takes place. As soon 

 as the protoplasm of the epithelial cells appears orange, the 

 extraction of the stain may be checked by washing in ben- 

 zole, and the sections may then be mounted in the usual way 

 in balsam. The zymogen granules are stained of an intense 

 blue color, the nuclei blue, other portions of the cells orange. 

 The stain is most successful after fixation in aqueous 

 sublimate. 



The earliest stages in the formation of the gastric glands 

 are difficult to discern, owing to the great number of yolk spher- 

 ules present which obscure the outlines of the cells. In a 

 larva 1 1 mm. long the glands are already visible as tubular 

 down-growths of the endoderm of the foregut. In this early 

 larva two kinds of glands are already to be recognized, those 

 occupying the anterior end just behind the tracheal groove, 

 and those at the posterior end, where the -stomach is' as yet 

 not clearly marked off from the general endoderm. The ante- 

 rior glands are of a flask-like shape, and have a distinct lumen 

 surrounded by a single layer of cells. Zymogen granules are 

 not yet to be recognized, and the yolk spherules are so abun- 

 dant that the outlines of the cells are not visible. In the lumen 

 there may often be seen one or two cells, which have been, so 

 to speak, squeezed out of the row of endoderm cells forming 

 the gland. These cells do not take any part in the formation 

 of the permanent histological elements, but may often be 



