Il6 VARIATION 



Up to this point in the experiment each generation required 

 two years, as the toadflax is a biennial, not blooming until the 

 second year. After this, however, the seedlings were started 

 under glass and transplanted to the garden in June. By this 

 means the new plants were made to produce flowers and seeds 

 the first year. 



About twenty plants of this (fourth) generation were secured, 

 and under this treatment most of them produced seed the first 

 year. Only one peloric flower was observed, however, in the 

 entire lot. The plant bearing this flower and one other were 

 preserved, and all others were destroyed. These two fertilized 

 each other freely and produced 10 cc. of seed, but no more 

 peloric flowers appeared. It is from this pair of plants, how- 

 ever, that a peloric race finally sprung. 1 



In 1894 about fifty plants were in flower. There was no rea- 

 son for considering these plants any more promising than pre- 

 vious sowings, except that " stray peloric flowers were observed 

 in somewhat larger numbers than in previous generations, 

 eleven plants bearing one or two, or even three, such abnor- 

 malities." De Vries wisely remarks that this ''could not be 

 considered as a real advance, since such plants may occur in 

 varying though ordinarily small numbers in every generation." 



However, besides these eleven individuals, each bearing one 

 or two abnormal flowers, there was a single plant bearing only 

 peloric flowers. The mutation had arisen and De Vries "was 

 present at the time." 



This plant was carefully kept, all others being destroyed, and 

 the next year it bloomed again, bearing only peloric flowers. It 

 was true to its type. In this connection De Vries says : 



Here we have the first experimental mutation of a normal into a peloric 

 race. Two facts were clear and simple : [first] the ancestry was known 



1 It has been said that the flowers of one plant are sterile to pollen from the 

 same plant. De Vries ascertained by careful experiment that this is true in about 

 50 per cent of the cases, so that, though a much higher degree of fertility exists 

 between individuals than within the individual, absolute barrenness between all 

 flowers of the same plant cannot be asserted. The point is not significant in the 

 present connection, but it is important as demonstrating that fertility and sterility 

 are not always in direct proportion to consanguinity, and that, though close breed- 

 ing may be commonly infertile in certain strains, it by no means follows that it is 

 always infertile even in the same strain. 



