Chapter XIII: The Notochord and Alimentary Canal

Relationship between notochord and gut--Position of unsegmented tube
of notochord--Origin of notochord from a median groove--Its function
as an accessory digestive tube--Formation of notochordal tissue in
invertebrates from closed portions of the digestive tube--Digestive
power of the skin of Ammocoetes--Formation of new gut in Ammocoetes
at transformation--Innervation of the vertebrate gut--The three
outflows of efferent nerves belonging to the organic system--The
original close contiguity of the respiratory chamber to the cloaca--
The elongation of the gut--Conclusion 433