THE FORMATION OP VARIETIES. 183 



ties of the Belgian canary-bird, remarks, 'Fanciers 

 always go to extremes; they do not admire indefinite 

 properties.' " 



He continues: 



"This principle, which necessarily leads to diver- 

 gence of character, explains the present state of various 

 domesticated races. We can thus see, how it is that 

 race-horses and dray-horses ; greyhounds and mastiffs ; 

 which are opposed to each other in every character, 

 — how varieties so distinct as Cochin-China fowls, 

 and bantams; or Carrier Pigeons with very long 

 beaks, and Tumblers with excessively short beaks; 

 have been derived from the same stock. As each 

 breed is slowly improved, the inferior varieties are 

 first neglected, and finally lost. * * * Selection, 

 whether methodical or unconscious, always tending 

 toward an extreme point, together with the neglect, 

 and slow extinction, of the intermediate and less valued 

 forms, is the key which unlocks the mystery how man 

 has produced such wonderful results * * * Con- 

 tinued divergence of character depends on, and is, in- 

 deed, a clear proof, as previously remarked, of the same 

 parts continuing to vary in the same direction." 



Instead of the pressure of degeneration being re- 

 lieved in every part, in every individual, it is relieved, 

 and reversion allowed to operate, solely in one part, or 

 in a few parts, in each variety of the species. With 

 the Pigeon, and with some other animals, all, or almost 

 all of the characters of the species are regained; but 

 they are suffered to be developed, not in each indi- 

 vidual, or variety, but in different individuals or varie- 

 ties. Then, many characters are reduced or suppressed, 

 either directly by man, or owing to disuse. This dis- 

 use would not reduce the characters, were a reasonable 



