384 Tricotylons Races. 



Oenothera nibrincri'is. In the pedigree of the Laevi- 

 folia family on p. 273 of the first volume, the origin of 

 two specimens of 0. rubrinervis is recorded for the year 

 1889. In the generations which were raised from these 

 two mutants, no tricotyls were at first observed (1890- 

 1891). They first appeared in the spring of 1892, and 

 with them the culture of the tricotylous half race began. 

 I selected the tricotyls from amongst thousands of seed- 

 lings and planted them out singly in pots with well 

 manured soil. I obtained 22 strong plants which flowered 

 freely in an isolated spot. The seeds were saved sep- 

 arately from each parent, each of which was labelled 

 according to its individual vigor. The five strongest 

 plants gave respectively 1.5, 1.9, 2.3, 2.6, and 2.8% trico- 

 tyls amongst from 700 to 900 seedlings. The remainder, 

 the weaker plants, only 0-1% With an average of 0.7% 

 amongst 8000 seedlings. The value 2.8% was obtained 

 from a very vigorous plant; in the three following gen- 

 erations it has hardly been reached again, in spite of 

 selection, and never was really exceeded. 



The ofl^spring of only the five best plants were 

 planted out and in all cases only tricotylous individuals. 

 There were about 70 of them and they were potted singly 

 and well manured (1893). In the middle of May they 

 were planted out into the bed at distances of about 30 

 centimeters apart, wdiere they flowered in isolation in 

 August, and could be mutually fertilized by insects. In 

 the spring of 1894 the seed of each plant was sown sep- 

 arately, and when the cotyledons had completely unfolded 

 the seedlings were recorded, 300 for each parent but 

 1000 or more in the 20 which appeared to be the best. 

 Altogether 45,000 seedlings were recorded, and amongst 

 these w^ere 170 tricotyls, i. e., about 0.4%. Of these 



