VZ8 CLASaiFIOATION, 



CHAPTER XIV. 



MUTUAL AFFIliTITIES 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 — 

 Affiflities, general, complex and radiating — Extinction separates 

 and defines groups — Morphology, between members of the same 

 class, between J)arts 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. 



Prom 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 signiiicance, 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 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., Conse- 



