Tricotyloiis Races Do Not Arise by Selection. 407 



by peculiarly favorable circumstances which were not 

 repeated in the following year. 



The repetition of tlie experiment in 1899 gave prac- 

 tically the same result. 



All in all, in the ten generations of my experiment, 

 there occurred neither a sudden nor a gradual transition 

 to an intermediate race. 



And lastly let me summarize the whole culture in a 

 simple table which gives only the mean and the highest 

 value for each generation as well as the value for the 

 seed-parent selected for the continuation of the race. 



The whole series, with the exception of the maximum 

 figures for 1897 rather indicates a fluctuating around a 

 constant mean value than a steady progress under the 

 influence of selection. 



Scrophularia nodosa. Of this species a series of 

 forms occurs. Their characters have been given in the 

 Prodrouius of De Candolle. The leaves are broadly 

 cordate or only rounded at the base, with little teeth of 

 almost uniform size, or very coarsely and irregularly 

 indented, and tiie fruits are large or small. The form 

 with cordate, tiniformly toothed leaves is very common, 

 in this neighborhood, and, so far as I know, the only 



