Chapter I: The Evidence of the Central Nervous System

Theories of the origin of vertebrates--Importance of the central
nervous system--Evolution of tissues--Evidence of Palæontology--
Reasons for choosing Ammocoetes rather than Amphioxus for the
investigation of this problem--Importance of larval forms--
Comparison of the vertebrate and arthropod central nervous
systems--Antagonism between cephalization and alimentation--
Life-history of lamprey, not a degenerate animal--Brain of
Ammocoetes compared with brain of arthropod--Summary 8