Amoeba: Its anatomy and physiology.--Development of the
cell.--Hydra: The development of digestive and reproductive organs,
and of tissues.--Forms intermediate between amoeba and hydra:
Magosphæra, volvox.--Embryonic development.--Turbellaria: Appearance
of a body wall, of ganglion, and nerve-cords.


CHAPTER III

WORMS TO VERTEBRATES: SKELETON AND HEAD

Worms and the development of organs.--Mollusks: The external
protective skeleton leads to degeneration or stagnation.--Annelids
and arthropods: The external locomotive skeleton leads
to temporary rapid advance, but fails of the goal.--Its
disadvantages.--Vertebrates: The internal locomotive skeleton leads
to backbone and brain.--Reasons for their dominance.--The primitive
vertebrate.


CHAPTER IV

VERTEBRATES: BACKBONE AND BRAIN

The advance of vertebrates from fish through amphibia and reptiles
to mammals.--The development of skeleton, appendages, circulatory
and respiratory systems, and brain.--Mammals: The oviparous
monotremata.--Marsupials.--Placental mammals.--Development of the
placenta.--Primates.--Arboreal life and the development of the