. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. No. 3.] OESOPHAGEAL GLANDS OF URODELA. 99 of the larval Amblystoma, and in the case of Necturus I have satisfied myself, by comparison of the actual objects, that the structures are identical. « The latest larva examined was 65 mm. in length. This animal was apparently about to undergo metamorphosis, as the stratified epithelium of the mouth had been replaced by ciliated. The pyloric glands were fully developed, and the ordinary gas- tric glands had assumed the appearance they present in the adult. The anterior portion of th
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. No. 3.] OESOPHAGEAL GLANDS OF URODELA. 99 of the larval Amblystoma, and in the case of Necturus I have satisfied myself, by comparison of the actual objects, that the structures are identical. « The latest larva examined was 65 mm. in length. This animal was apparently about to undergo metamorphosis, as the stratified epithelium of the mouth had been replaced by ciliated. The pyloric glands were fully developed, and the ordinary gas- tric glands had assumed the appearance they present in the adult. The anterior portion of the stomach, about a millimeter in extent, was still ciliated, but the saccular glands of this region had undergone considerable modification. One of these is shown in Fig. 7. It will be seen that the base of the gland has grown out into a num- ber of short secondary tubules, formed for the most part of zymo- genic cells, and the gland now consists of a large number of such tubules, each similar in structure to an ordinary gastric gland, opening into a large common cavity lined by transparent mucous cells corresponding to the neck cells of an ordinary gland. In short, the saccular gland of the embryo is being transformed into an anterior oxyntic gland of the adult. Two of the most anterior glands in this larva were included in the oesophagus. All were in full physiological activity and were filled with granules. I have been unable to secure a specimen of Amblystoma undergoing metamorphosis, or one that has just completed it, and am therefore unable to state positively whether all the sac- cular glands become transformed by subsequent branching into anterior oxyntic glands, or some of them degenerate and dis- appear. There is in the latest larva that I have examined no evidence of changes of a degenerate nature, and I am there- fore inclined to believe that the most anterior glands, as well as the rest, are taken up into the stomach, and that the oesophagus. FIG. 7. —O
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