402 CLASSIFICATION. 



CHAPTER XIV. 



MUTUAL AFFINITIES OF ORGANIC BEINGS : MORPHOLOG* — 

 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 

 nad 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 

 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 the dominant species, 

 belonging to the larger genera in each class, which vary 

 most. The varieties, or incipient species, thus produced, 

 ultimately become 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, tend to go on increasing in size. I further 

 attempted to show that from the varying descendants of each 

 species trying to occupy as many and as different places as 

 possible in the economy of nature^ they constantly tend td 



