44 Dynamic Evolution 



mature, the inherited energy might be pushed 

 forward into the immature stage, and what 

 started as a secondary sexual character might 

 become an ordinary character and be trans- 

 mitted to offspring of the opposite sex. The 

 facts of physics and biology make it a wise 

 precaution to take this into consideration, 

 and the facts of pedigree records show that a 

 failure to consider it would result in confusion 

 and misinterpretation. 



This possible shift of characters might be 

 of relatively small importance when the 

 energy characteristics are practically uni- 

 form for all individuals in successive genera- 

 tions, but it assumes very great importance 

 when periods of work and idleness are highly 

 variable both as to degree and time in life 

 when they occur. With trotting horses these 

 are extremely variable. Some horses do hard 

 work nearly all their lives, other horses work 

 hard at one age and are idle at other ages, 

 other horses have the times of work and idle- 

 ness reversed, and still other horses are idle 

 nearly all their lives. In any horse pedigree, 



