In a study of the =trunk=, note the tail, the allantois, Wolffian ridges, the heart, and the condition and the position of the rudimentary limbs. Make drawing of embryo from the side view. Carefully cut off the head immediately behind the last visceral arch, and study and draw the structures observed on the ventral side. Note the maxillary processes, the mandibular and the hyoid arch, the nasal pits, and the fronto-nasal process, which is just beginning its development. In a study of transverse sections observe from your drawing at what level the section is made. Study and draw a section made through the region of the anterior limbs. Note the spinal ganglion, the muscle plate, or myotome, the condensation of mesenchyme around the notochord, the pancreas, the liver, and the intestine; and note the distribution of the mesenchyme. Note the ventral roots of the spinal nerves, and the neuroblasts in the spinal cord. In sectioning the embryo from before backward, the first sections will pass horizontally through the hindbrain and the midbrain region. Note the parts, including the auditory vesicle. In the first series of sections also locate the ganglia of the pneumogastric, or vagus, the acoustico-facialis, the trigeminus, and the glosso-pharyngeal nerves. Note the notochord and the cardinal veins. After the disappearance of the ear, we observe the midbrain, which, is located at one end of the section, and the cord at the other end. The region between lies just above the pharynx. In the following series study the visceral arches. Note the third pair of cranial, or motor ocular, nerves. This latter nerve springs from the floor of the midbrain. From the ventral prolongation of the floor of the thalamencephalon there arises the infundibulum. The hypophysis is located just beneath the infundibulum. At this stage the hypophysis appears as a tube to empty into the mouth. This is an ingrowth of the oral epithelium. In a study of a section through the center of the eye we should observe the lens and optic stalk. This is in the region of the optic chiasm. Note the choroid fissure and the pineal gland, the latter appearing just beyond the eyes. Just forward lies the telencephalon, or rudiments of the cerebral hemispheres. In a study of the =alimentary tract= we note that the mouth is bounded by the mandibular arches. Note the maxillary processes, and the ventral surface of the head. A finger-like diverticulum, extending from the roof of the ruptured double membrane, formerly separating the pharynx from the arches, forms the hypophysis. The great development of the visceral pouches makes the pharynx rather complex. In studying sections horizontally through the pharyngeal region note the various visceral arches and pouches. Note the arteries of the thyroid diverticulum.