534 Franklin P. Johnson. 
cells are again in their upper ends. The epithelium on the side 
toward the bursa omentalis shows several irregularities. These are 
vacuoles and pit-like depressions. The vacuoles are similar to 
those found in the cesophagus, but are smaller and far less num- 
erous. The pit-like depressions are surrounded on their sides by 
the columnar cells of the epithelium. The nuclei of the cells 
which line the pits are rounded and are quite regularly placed 
around the lumen, so that the whole structure has somewhat the 
appearance of a taste bud. The pits measure about .009 mm. in 
width and about .028 mm. indepth. There are no corresponding 
outbulgings of the basement membrane made by these pits on 
the mesenchymal surface of the epithelium. 
In an embryo of 19 mm. the epithelium of the stomach is of 
the same type as in the preceding embryo, having two or three 
layers of cells and a thickness of .048 mm. It contains a few small 
vacuoles. The pits are more numerous than before and some are 
elongated so that now they form short grooves. These are most 
numerous in the lower end of the stomach. Again there is nothing 
on the mesenchymal side of the epithelium to correspond to these 
depressions. In this embryo the beginning of the tunica muscu- 
laris is first seen. 
The epithelium of the stomach at 22.8 mm. measures on the 
average .055 mm. in thickness. A few vacuoles, similar to those 
found in the cesophagus of this embryo, were observed. They 
were, however, much smaller than those in the cesophagus. The 
pits are more numerous and distinct than in the preceding embryo. 
Again some are rounded and some groove: like in form, but still 
they produce no swellings on the under side of the epithelium. 
At 42 mm. the pits are abundant. The epithelium measures .055 
mm. in thickness and shows for the first time slight bulgings into 
the mesenchyma. 
In an embryo of 55 mm. the epithelium of the stomach shows 
well defined pits and furrows on its inner surface. A surface 
view of a portion of the epithelium of the fundus of the stomach 
at this stage is shown in fig. 10. The cylindrical pits are irregularly 
scattered about, and the grooves are placed parallel to the long 
axis of the stomach. The epithelium, which was previously 
