106 Dynamic Evolution 



Female A nceslors for 5 Generations 



Dams with Records Dams without Records 



No. Av. Ages No. Av. Ages 



58 Stallions 34 14.85 692 12.86 



66 Mares 42 13.19 718 12.92 



56 Geldings 38 13.80 512 12.49 



114 1922 



The significance of these tables does not 

 reside in the fact that they include the ages 

 of more than 5000 sires and dams, but in the 

 fact that they cover all of the generations 

 involved in the production of 2 : 10 trotters 

 from an original stock not capable of trotting 

 a mile in three minutes. They tell us that 

 each increase of energy, generation by genera- 

 tion through a century of time, came from 

 animals which did an excessive amount of 

 work before reproducing, and that when any 

 part of a generation failed to perform such 

 work before reproducing, then no correspond- 

 ing increase of energy was found in the off- 

 spring of that part. They also tell us that 

 when work is performed in one generation 

 sufficient to cause an increase of energy in 



