CHAPTER IV.. Special Proofs From the General Laws of Animal Structure, or

SPECIAL PROOFS FROM THE GENERAL LAWS OF ANIMAL STRUCTURE, OR COMPARISON IN THE TAXONOMIC SERIES.

General Principles.

Analogy and homology--Defined and illustrated by examples-- Wings and limbs--Lungs, gradual formation of, traced in the Taxonomic series--Traced in the Ontogenic series--Examples of homology in plants: tuber, cactus-leaf, acacia-leaf-- Definitions repeated and further explained--Common origin is the only explanation of homology 99

Primary divisions of the animal kingdom--True ground of such divisions is ability to trace homology--We take examples only from vertebrata and articulata--Compare to styles of architecture--To machines--To branching stem 107