Monstrosities 423 



reached ; so for instance with the mercury, I had 

 three succeeding generations of selection after 

 reaching the average of 55^, but their extremes 

 gave no increasing advance, remaining at 86, 92 

 and 91^. 



If we compare these results with the effects 

 of selection in twisted and fasciated races, we 

 observe a marked contrast. Here they reached 

 their height at 30 - 40%, and no number of gen- 

 erations had the power of making any further 

 improvement. The tricotyls come up in two 

 generations to a proportion of about 54^, which 

 shows itself to correspond to the average 

 type. And as soon as this is reached, only one 

 generation is required to obtain a very consid- 

 erable improvement, going up to 80 or even 90^. 



It is evident that the cause of this difference 

 does not lie in the nature of the monstrosity, but 

 is due to the criterion upon which the selection 

 is made. Selection of the apparently best in- 

 dividuals is one method, and it gives admirable 

 results. Selection on the ground of the hered- 

 itary percentages is another method and gives 

 results which are far more advantageous than 

 the former. 



In the lecture on the pistillody of the poppies 

 we limited ourselves to the selection of the finest 

 individuals and showed that there is always a 

 manifest correlation between the individual 



