CLAHiilFlCATION 211 



CHAPTER XIV 



MUTUAL AFFINITIES OF ORGANIC BEINGS: MORPHOLOGY: 

 EMBRYOLOGY: RUDIMENTARY ORGANS 



Classification, groups subordinate to groups — Natural system — Rules 

 and difficulties in classification, explained on the theory of descent with 

 modification — Classification of varieties — Descent always used in classi- 

 fication — Analogical or adaptive characters — Affinities, general, com- 

 plex, and radiating — Extinction separates and defines groups — 

 Morphology, between members of the same class, between parts of 

 the same individual — Embryology, laws of, explained by variations not 

 supervening at an early age, and being inherited at a corresponding age 

 — Rudimentary organs; their origin explained — Summary 



Classification 



FROM the most remote period in the history of the 

 world organic beings have been found to resemble 

 each other in descending degrees, so that they can 

 be classed in groups under groups. This classification is 

 not arbitrary like the grouping of the stars in constella- 

 tions. The existence of groups would have been of 

 simple significance, if one group had been exclusively 

 fitted to inhabit the land, and another the water; one to 

 feed on flesh, another on vegetable matter, and so on; 

 but the case is widely difl'erent, for it is notorious 

 how commonly members of even the same sub-group 

 have different habits. In the second and fourth chap- 

 ters, on Variation and on Natural Selection, I have 

 attempted to show that within each country it is the 

 widely ranging, the much diffused and common, that is 



