Mucous Membrane in the Human Embryo. 533 
tric mucosa in eat, pig, and human embryos, concluded that the 
glands are formed exclusively by downgrowths from the epithe- 
lium. Minot (’02) likewise describes an epithelial origin for the 
glands. Later, Strecker (’08) returned to the old idea of a mesen- 
cymal origin for the gland cells. The results of the present work 
are largely in accord with those of Toldt. However the present 
study deals mainly with the form of the mucous membrane and 
is based upon a series of wax reconstructions, while Toldt was con- 
cerned chiefly with detailed histogenesis. 
Early Stages. In an embryo of 7.5 mm. the stomach is a wel! 
marked, spindle-shaped swelling, about .132 mm. in transverse 
diameter. It is placed with its long axis parallel to the long axis 
of the body of the embryo. Its epithelium is about .046 mm. in 
thickness and at the extremities of the stomach is composed of 
two or three layers of low columnar cells, at the mid region of 
higher columnar cells. As in the oesophagus, the basal layer of 
cells is the tallest, and the nuclei are placed at the upper ends of 
the cells. In an embryo of 8 mm., described by Jahrmeerker, 
the nuclei of this strata were found in the basal ends of the cells, 
and this he pointed out as a distinction between cesophagus and 
stomach at this stage. The epithelium of the stomach is sur- 
rounded by loose mesenchyma which is limited, except at its 
mesenteric attachments, by the mesothelial lining of the coelom. 
In an embryo of 10 mm. the stomach is more pyriform in shape 
and is now undergoing rotation to the right on its long axis. 
The lumen has greatly increased in diameter but the epithelial 
wall is of about the same thickness, measuring .048 mm. The 
number of strata of cells varies from two to three. Both the 
basal and the superficial layers of cells are distinctly columnar 
the latter showing distinct top plates. The nuclei of the basal 
layer are again in the upper ends of the cells, those of the super- 
ficial layer at the lower ends. The surrounding mesenchyma is 
slightly condensed, and a basement membrane is distinct in some 
places. 
Gastric Pits. At 16mm. the stomach is lined by an epithelium 
of high columnar cells of two or three layers, the entire thickness 
of the wall measuring .054 mm. The nuclei of the basal layer of 
