CHAPTER VIII 214-230

UNITY OF TYPE IN THE GREAT CLASSES; AND MORPHOLOGICAL STRUCTURES.

Unity of Type Morphology Embryology Attempt to explain the facts of embryology On the graduated complexity in each great class Modification by selection of the forms of immature animals Importance of embryology in classification Order in time in which the great classes have first appeared

ABORTIVE OR RUDIMENTARY ORGANS.

The abortive organs of Naturalists The abortive organs of Physiologists Abortion from gradual disuse