differentiated into muscle fibers, figure 7J, _ml_, which form a
fairly distinct layer; inside of this layer is a tall columnar
epithelium, _ep'_, which is thrown into prominent folds. A thin layer of
mesoblast, probably the submucosa, _sl_, lies beneath the epithelium and
projects up into the folds. About ten or twelve folds are seen in any
one section; only the larger ones are well seen in figure 7D.

Figure 7E shows a section through the plane 770 of figure 7. It is in
the region of the umbilicus, _u_, and the extreme caudal end of the
stomach which has been called the gizzard, _gz_. The small size of the
gizzard is due to its being cut near its caudal margin. The enteron is
here cut in no less than seven places: the reason for this will be
evident on examination of the plane of the section as shown in figure 7.
Dorsal to the gizzard the section cuts the so-called caecum, _ce_,
a little nearer its anterior end than is shown in figure 7. The
duodenum, _d_, is cut at five points, and has about the same structure
as in the preceding figure. The character of the duodenal loops that
causes the rather curious appearance of the present figure will be
readily understood by reference to figure 7, though the reconstruction
is not mathematically accurate. The ventral projection of the lower
loops of the duodenum into the umbilicus is seen both in the present
figure and in the reconstruction. The loop of the duodenum that, in the
sections, is seen to lie directly ventrad to the gizzard, in the
reconstruction is shown too much to the side of the latter organ. The
descending loops of the duodenum are cut in such a way that the
surrounding mesoblast forms a continuous mass of tissue.

Figure 7F represents a section through the plane 901 of figure 7. The
section passes through the kidneys, _k_, the edge of one posterior
appendage, _pa_, the large intestine, _il_, and two regions of the small
intestine, _i_.

The large intestine is here a thick walled, cylindrical structure, _il_,
hanging from a thin mesentery, _ms_, in the much reduced body cavity.
The layers of its wall are much more fully differentiated than in the
more anterior regions of the enteron. The epithelium is here stratified
instead of simple columnar, and the folds into which it is thrown are
broader and less numerous than in the duodenum above described.

Ventrad to the large intestine, and almost in contact with it, is seen
the allantois, _al_, whose general outl