CHAPTER X.. The Alimentary Canal, Pp. 446-459.

THE ALIMENTARY CANAL, pp. 446-459.

The solid oesophagus.--OEsophagus originally hollow. Becomes solid during Stage K. The postanal section of the alimentary tract.--Continuity of neural and alimentary canals. Its discovery by Kowalevsky. The postanal section of gut. Its history in Scyllium. Its disappearance. The cloaca and anus.--The formation of the cloaca. Its junction with segmental ducts. Abdominal pockets. Anus. The thyroid body.--Its formation in region of mandibular arch. It becomes solid. Previous investigations. The pancreas.--Arises as diverticulum from dorsal side of duodenum. Its further growth. Formation of duct. The liver.--Arises as ventral diverticulum of duodenum. Hepatic cylinders. Comparison with other types. The subnotochordal rod.--Its separation from dorsal wall of alimentary canal. The section of it in the trunk. In the head. Its disappearance. Views as to its meaning.