s of transverse sections through an embryo of the
age shown in figure 5. x 7.

Figure 5J. A composite drawing of reconstructions of the enterons of two
embryos of the age of the one shown in figure 5. One reconstruction was
in wax, from sagittal sections, the other was a plotted reconstruction
from transverse sections. x 14.

Figure 6. A surface view, in profile, of an embryo with well developed
manus and pes. x (about) 5.

Figure 6A. A reconstruction, plotted from transverse sections, of the
enteron of an embryo of about the age of the one shown in figure 6.
x 14.

Figures 6B-6H. Part of a series of transverse sections from which the
preceding reconstruction was made. x 7.

Figure 7. A reconstruction of the enteron of an embryo of 42 mm.
crown-rump length.

Figures 7A-7G. A part of the series of transverse sections from which
the preceding reconstruction was made. x 7.

Figure 7H. A high power drawing of a portion of the wall of the
oesophagus in the region of figure 7A. x 190.

Figure 7I. A high power drawing of a portion of the wall of the stomach
in the region of figure 7C.

Figure 7J. A high power drawing of a portion of the wall of the duodenum
in the region of figure 7D.

Figure 8. An outline drawing, from the ventral aspect, of the enteron of
an embryo of 20 cm. length, at about the time of hatching; made from a
dissection. x 1.

LETTERING FOR ALL FIGURES

_a_, head-fold of amnion.
_aa_, anterior appendage.
_ac_, anterior cardinal vein.
_aip_, anterior intestinal portal.
_al_, allantois.
_an_, anterior nares.
_ao_, aorta.
_ar_, aortic arch.
_au_, auricle.
_b_, bulbus arteriosus.
_bc_, body cavity.
_bd_, bile duct.
_bd'_, opening of bile duct to liver.
_bd''_, opening of bile duct to duodenum.
_blp_, blastopore.
_bp_, basilar plate.
_bs_, bile-sac.
_bv_, blood vessel.
_c_, centrum of vertebra.
_ca_, caudal artery.
_ce_, caecum.
_ch_, cerebral hemisphere.
_cl_, cloaca.
_cm_, circular muscle layer.
_cn_, cranial nerve.
_cp_, posterior choroid plexus.
_cv_, cardinal vein.
_d_, duodenum.
_dc_, ductus Cuvieri.
_di_, diverticulum of stomach.
_e_, eye.
_ec_, ectoderm.
_ec'_, thickening of ectoderm.
_en_, entoderm.
_en'_, endocardium.
_ent_, enteron.
_ep_, epidermal layer of ectoderm.
_ep'_, epithelium.
_epi_, pineal body.
_es_, embryonic shield.
_f_, fronto-nasal process.
_fb_, forebrain.
_