84 NEW DIMORPHIC MUTANTS OF THE OENOTHERAS. 



With one of them, 0. cana, 1 have made a number of crosses with 

 allied forms, in order to ascertain that it behaves in the same manner 

 as 0. scintillans, and that the same conception of heterogamy must 

 be applied here also. In this mutant the pollen carries only the 

 hereditary qualities of 0. Lamarckiana, and the specific marks of 

 the mutant are handed down to their progeny through the ovules 

 only. 1 ) This conception of heterogamy may be considered to hold 

 good for the other inconstant types also. 



The same behavior is found in 0. lata, but since this form never 

 produces any fertile pollen in my cultures and has to be fertilized 

 by 0. Lamarckiana in order to produce seeds, the evidence which 

 it affords is less stringent than that given by the self-fertile dimor- 

 phic races. 



Oenothera Lamarckiana mut. cana.— Among a number of dubious 

 mutants from 0. lata which were cultivated as biennials in 1906-1907, 

 a plant was noticed in the third generation of that family with 

 narrower leaves of a gray color, evidently constituting a new type. 

 It was very vigorous, reached a height of about 2 m., and was 

 self-fertilized. It will be designated as 0. cana from lata no. 1, 

 since the first family of 0. cana was derived from it. 



Next year the same mutant type was recognized among the 

 young rosettes, issuing from different samples of seeds of 0. lata 

 (fig. 1). All in all there were 5 specimens of 0. cana. In order to 

 determine the frequency of this mutant I have made two cultures 

 on a sufficiently large scale, using the seeds produced by my pure 

 strain of 0. lata fertilized by 0. Lamarckiana. The seeds of 1909 

 gave 564 seedlings, with 18 per cent lata and 2 per cent cana. Those 

 of 1908 gave 1550 seedlings, 8 per cent of which were lata and 9 per 

 cent were cana. Other mutants appeared in these cultures in different 

 proportions, as usual. 



Among the seeds of pure 0. Lamarckiana, 0. cana is much the 

 rarer. In 1913 I fertilized, on 5 strong biennial specimens, almost 

 all the flowers during two months and got sufficient seed to have 

 20,000 seedlings in 1914. Of these only 6 were cana, giving a per- 

 centage of 0.03 per cent. In the same boxes 7 rubrinervis and 5 

 scintillans appeared as mutants, showing that the mutation coeffi- 

 cients for these three forms do not essentially differ from one another. 



fertile and much stronger than the mutant form. As a matter of fact, 

 inconstant wild species of this type are not known. See The mutation 

 theory, Vol. I, p. 380. 



1) Gruppenweise Artbildung, p. 273, 19 13. 



