ch more nearly fill the body cavity than in the
preceding figure. The section being caudad to their openings into the
lungs the bronchi do not, of course, show.

The oesophagus, _oe_, is here of much less diameter than in the
preceding figure, but is still laterally compressed. Its wall is
somewhat thicker than in the more cephalic region, the increase being
mainly due to the greater thickness of the connective tissue layer,
though the epithelium is also slightly thicker because of an increase in
the length of the lining cells. Instead of lying almost entirely ventrad
to the lungs, as in the preceding figure, the oesophagus here lies
directly between them.

Figure 7C represents a section through the plane 627 of figure 7. The
plane of the section passes through the opening of the stomach, _i'_,
into the duodenum, _d_. The cross section of the stomach is somewhat
larger than that of the oesophagus, but it differs from the more
anterior region mainly in the character of its walls. These are much
thicker than in the oesophagus; in the mesoblast which forms the greater
part of their thickness, muscle fibers are beginning to differentiate.
The epithelial layer also is thicker than in the oesophagus; it consists
of tall columnar cells that, at places, are thrown into small folds,
figure 7I. These folds, even under the low magnification used, are more
evident than is shown in the present figure. The pylorus, _py_, is wide
and, as has been noted in connection with figure 7, is situated far
cephalad to the caudal end of the stomach. It opens into the side rather
than into the end of the duodenum, which projects cephalad as a short
blind pouch, _d_. The stomach and duodenum, in this section, are almost
completely surrounded by the liver, _li_.

Figure 7D represents a section through the plane 680 of figure 7.

The stomach, _i'_, which is cut through its middle region, is somewhat
larger than in the preceding figures, though its walls have about the
same character. Its outer walls are continuous, to a considerable
extent, with the tissue of the surrounding body wall, especially in the
region just caudad to the plane of the present section.

The duodenum, being cut through a double loop (see figure 7), is seen in
two places, dorsally where it is cut through the edge of one loop, and
ventrally where it is cut square across. In both sections the structure
is the same, as might be expected, figure 7J. The surrounding mesoblast
is