160 SALMONIA. 



his muscles acquire their power by habit; 

 their motions are at first automatic, and be- 

 come voluntary by associations, so that a child 

 must learn to walk as he learns to swim or 

 write ; but in the colt or chicken, the limbs 

 are formed with the powers of motion, and 

 these animals walk as soon as they have quit- 

 ted the womb or the egg. 



PHYS. I believe it possible, that they may 

 have acquired these powers of motion in the 

 embryo state ; and I think I have observed, 

 that birds learn to fly, and acquire the use of 

 their wings, by continued efforts, in the same 

 manner as a child does that of his limbs. 



ORN. I cannot agree with you : the legs 

 of the foetus are folded up in the womb of the 

 mare ; and neither the colt nor the chicken 

 can ever have performed, in the embryo state, 

 any motions of their legs similar to those 

 which they have perfectly at their command 

 when born. Young birds cannot fly as soon 

 as they are hatched, because they have no 

 wing feathers ; but as soon as these are de- 

 veloped, and even before they are perfectly 

 strong, they use their wings, fly, and quit their 



