EVOLUTION OF MODERN FOWL 17 



The blacksmith's arm is a striking object lesson of the effect 

 of vigorous use of a part of the body. The poultryman 

 knows that exercise hardens the muscles of the chicken, and 

 when a tender article of chicken meat is desired, the fowls 

 are fattened in crates or small pens in order to keep them 

 from exercising. Whether the qualities of tenderness in the 

 meat could become a fixed and transmissible characteristic 

 may be open to debate ; but acquired characteristics some- 

 times become hereditary. The horse was originally a pacer ; 

 trotting is an acquired characteristic. Fowls were original- 

 ly all sitters, but certain breeds through disuse of sitting or 

 hatching have acquired the characteristic of non-sitting, 

 and they breed true to that characteristic. 



It is known that the wing of the tame duck has diminished 

 in weight in proportion to size of body and legs since domes- 

 tication, the tame duck being a descendant of the common 

 wild duck. The tame duck is much larger in limb and body 

 than its wild ancestor, and it has little or no use for its wings. 

 By use, the leg bones have increased in size, but by disuse 

 the wing bones have rather decreased. Under domestication, 

 the disproportion between strength of wing and ability to 

 fly, has become so great that a duck of the Pekin type would 

 make a spectacle of itself if on the wide-open prairie by the 

 use of its wings it sought to elude the pursuit of the coyote. 



The same thing is true to a greater or less extent in breeds 

 of chickens. The weight of wing bones is much less than 

 those of the wild ancestor, the jungle fowl, in proportion 

 to weight of leg bones. This is specially true of the heavier 

 breeds, since the Cochin and Brahma, for instance, very 

 seldom use their wings. 



Crossing. Probably the most fruitful source of varia- 

 tion, and therefore evolution, is the crossing of different 

 breeds or varieties. Before methodical selection was prac- 

 ticed, little consideration would be given to keeping breeds 



