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 classification — Analogical or adaptive characters 

 — Affinities, general, complex, and radiating — Extinction sepa- 

 rates 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 constellations. 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 different, for it is notorious 

 how commonly members of even the same sub-group have 

 different habits. In the second and fourth chapters, on Vari- 

 ation and on Natural Selection, I have attempted to show 

 that within each country it is the widely ranging, the much 

 dififused and common, that is the dominant species, belonging 

 to the larger genera in each class, which vary most. The 

 varieties, or incipient species, thus produced, ultimately be- 

 come converted into new and distinct species ; and these, on 

 the principle of inheritance, tend to produce other new and 

 dominant species. Consequently the groups which are now 

 large, and which generally include many dominant species, 



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