Inconstancy of Improved Races 789 



rows. Choosing always the principal ear, 

 the figures may be taken to indicate the de- 

 gree of personal deviation from the average of 

 the race. But whenever we make a mistake, and 

 perchance sow from an ear, the deviation of 

 which was largely due to partial variation, the 

 regression would be expected to become con- 

 siderably larger. Hence it must be conceded 

 that exact calculations of the phenomena of in- 

 heritance are subject to much uncertainty, 

 resulting from our very imperfect knowledge 

 concerning the real proportion of the contribut- 

 ing factors, and the difficulty of ascertaining 

 their influence in any given case. Here also we 

 encounter more doubts than real facts, and much 

 remains to be done before exact calculations 

 may become of real scientific value. 



Eeturning to the question of the effects of se- 

 lection in the long run, two essentially differ- 

 ent cases are to be considered. Extremes may 

 be selected from among the variants of ordinary 

 fluctuating variability or from ever-sporting va- 

 rieties. These last we have shown to be double 

 races. Their peculiar and wide range of vari- 

 ability is due to the substitution of two charac- 

 ters, which exclude one another, or if combined, 

 are diminished in various degrees. Striped 

 flowers and stocks, " five-leaved " clover, pis- 

 tilloid opium-poppies and numerous other mon- 



