202 



CLASSIFICATION. [Chap. XIV. 



CHAPTEE XIV. 



mutual affinities of ohganic beings: mob- 

 phology: bmbktologt: rudimentaky obgans. 



Classification, groups subordinate to groups— Natural system- 

 Rules and difficulties in classification, explained on the theory 

 of descent with modification— Classification of varieties— De- 

 scent always used in classification- Analogical or adaptive char- 

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

 separates and defines groups— Mokphology, between members 

 of the same class, between parts of the same individual— Em- 

 bryology, 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 arbi- 

 trary like the grouping of the stars in constellations. The 

 existence of groups would have been of simple signifi- 

 cance, if one group had been exclusively fitted to in- 

 habit 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 com- 

 monly members of even the same sub-group have dif- 

 ferent habits. In the second and fourth chapters, on 

 Variation and on Natural Selection, I have attempted 



