Chapter XIV: The Principles of Embryology

The law of recapitulation--Vindication of this law by the theory
advanced in this book--The germ-layer theory--Its present position--
A physiological not a morphological conception--New fundamental law
required--Composition of adult body--Neuro-epithelial syncytium and
free-living cells--Meaning of the blastula--Derivation of the
Metazoa from the Protozoa--Importance of the central nervous system
for Ontogeny as well as for Phylogeny--Derivation of free-living
cells from germ-cells--Meaning of coelom--Formation of neural
canal--Gastrula of Amphioxus and of Lucifer--Summary 455