6 Emil Goetsch. 
arations the branching of the tubule may be studied with ease, thus 
avoiding the laborious method of reconstruction from sections. 
Because of the lack of sufficient material I was unable to apply the 
method in the case of the wild animals whose cesophagi were exam- 
ined, but such preparations were made of all the domestic animals 
and of man. 
For staining sections hematoxylin and eosin, iron hematoxylin, 
copper chrome hematoxylin, neutral gentian, muchematein, mucicar- 
mine, Mallory’s connective tissue stain and acid violet-saffranin were 
employed. 
Opossum (Didelphys virginiana). 
The mucous membrane of the cesophagus of the opossum exhibits 
the usual transitory longitudinal folds observed in the empty 
cesophagus. About 1 em. above the cardiac orifice of the stomach, 
however, these disappear, and their place is taken by permanent 
- transverse folds of the mucous membrane approximately 0.5 mm. in 
width, and provided on their free surfaces with a network of second- 
ary ridges. These folds are separated from one another by deep 
sulci and, as will appear later, owe their occurrence in part to the 
accumulation in the lamina propria mucose of masses of glands. 
The epithelium of the cesophagus at its upper end is represented 
in Fig. 1. It consists of a layer of somewhat irregular thickness, 
owing to the projection into it, from below, of ridges longitudinal in 
direction, belonging to the lamina propria. In full grown animal 
weighing 3,000 grammes, the thickness of the epithelium at the 
level of the cricoid cartilage was, in the spaces between the con- 
nective-tissue ridges, 190-250 micra, on the summit of the ridges 
72-110 micra. The irregularity in thickness presented by this 
epithelium in transverse sections is due to high ridges of the lamina 
propria, which are for the most part longitudinal in direction, but 
are connected with one another by lower transverse and oblique ridges, 
so that in sections parallel to the surface at the level of the ridges 
a connective tissue network is seen surrounding islets of epithelium, 
instead of the epithelial network seen at this level in sections of the 
epidermis. As described by Oppel (97) in Phalangista, Phasco- 
larctus and Aepyprymnus, true papille are wanting in the opossum. 
