Chap, v.] HIGHLY VAEIABLB. 187 



ously shaken my belief in its truth, had not the great 

 variability in plants made it particularly difficult to 

 compare their relative degrees of variability. 



When we see any part or organ developed in a re- 

 markable degree or manner in a species, the fair pre- 

 sumption is that it is of high importance to that species: 

 nevertheless it is in this case eminently liable to varia- 

 tion. Why should this be so? On the view that each 

 species has been independently created, with all its 

 parts as we now see them, I can see no explanation. 

 But on the view that groups of species are descended 

 from some other species, and have been modified 

 through natural selection, I think we can obtain some 

 light. First let me make some preliminary remarks. 

 If, in our domestic animals, any part or the whole ani- 

 mal be neglected, and no selection be applied, that 

 part (for instance, the comb in the Dorking fowl) or 

 the whole breed will cease to have a uniform charac- 

 ter: and the breed may be said to be degenerating. 

 In rudimentary organs, and in those which have been 

 but little specialised for any particular purpose, and 

 perhaps in polymorphic groups, we see a nearly parallel 

 case; for in such cases natural selection either has not 

 or cannot have come into full play, and thus the or- 

 ganisation is left in a fluctuating condition. But what 

 here more particularly concerns us is, that those points 

 in our domestic animals, which at the present time 

 are undergoing rapid change by continued selection, 

 are also eminently liable to variation. Look at the 

 individuals of the same breed of the pigeon, and see 

 what a prodigious amount of difference there is in the 

 beaks of tumblers, in the beaks and wattle of carriers, 

 in the carriage and tail of fantails, &c., these being 



