The Isolation of Trkotyloiis Inlcnncdialc Races. 423 



SELECTIOxN' OF THOROUGHBRED TKICOTVLOI'S RACES. 



llEkEDITAKV VALLES OF THE BEST TRICOTVLOUS SEKD-l'AkENTS UE THE 



FOURTH GENERATION. 



THIRD 



GENER. 25 30 35 40 45 50 55 60 (o 70 75 80 85 



ATION 



jMercuria/is ainiiia 55% 12 2 12 12 3 1 



Silene inflata 55% 10234444711 



It \\ ill be seen that regression did not accompany this 

 ..election, because the parent plants deviated too little as 

 vet from the mean of the new race. On the other Irmd 

 the high values of 75-85% were immediately reached, 

 and this obviously indicates a considerable advance. These 

 instances, taken together with the table which will be 

 given on page 439, are sufficient to indicate the method 

 by which tricotylous intermediate races, if they are at 

 all present, can be isolated and improved. They will 

 facilitate the understanding of the detailed description 

 of my experiments. These obviously present, according 

 to the species investigated, greater or less deviations from 

 the instances given, but as a rule they are not essential 

 ones. Therefore I shall give these descriptions as briefly 

 as possible. 



But before doing so I wish once more to lay emphasis 

 on the fact that these cases are thoroughly distinct from 

 those in which only half races are present, and from 

 which, after several generations, often no more than 2 

 to 4% and only very rarely as much as 20% was reached, 

 as maximum figures (see table on page 392). 



Oenothera hirtella. Under this name I cultivate a 

 tricotylous race which I obtained by chance from bought 

 seed. In 1895 I was growing some samples of seed of 

 Oenothera Laniarckiana and allied species which had 



