NEW DIMORPHIC MUTANTS OF THE OENOTHERAS. 



S7 



per cent with a mean of 25 pei cent seem to indicate a splitting 

 into nearly equal parts, with a loss on the side of the weaker form. 

 The same deviation from equality will be seen in almost all the 

 figures of this article, and the same explanation must be considered 

 as applying to all of them. It is almost always the new type which 

 is in the minority. 1 ) 



The seeds of the Lamarckiana-Uke individuals do not give rise 

 to a splitting of this kind, keeping true to their parent form. The 

 same fact recurs in all the pedigrees to be mentioned later on, and 

 for all the new dimorphic types. It may be taken to be the rule, 

 therefore, although the trials have been only one or two in each 

 instance. It agrees fully with the behavior of the analogous split- 

 ting products of 0. scintillans. 



0. cana from lata nos. 2 and 3.— In a culture of about 600 

 seedlings of 0. lata, 4 mutants of the cana type arose in 1908. The 

 lata strains had been derived from some annual mutants which 

 had been produced by my 0. Lamarckiana in 1905, and described 

 in my Gruppenweise Artbildung (p. 247). From these mutants a 

 second generation was cultivated in 1907, and fertilized by the 

 pollen of Lamar xkiana-Wke individuals of the same culture. Their 

 seeds yielded the two cana mutants to be described here, and two 

 others, from the seed of which only one generation has been studied. 



The pedigree of mutant no. 2 is given below: 



1908 ....Mutant 



Mutant 



1912 .... Second generation 35 per cent cana 



'Lamarckiana 



1913 ....Third generation 15 per cent cana ^Lamarckiana 



That of mutant no. 3 was as follows: 



1908 ....Mutant Mutant 



1913 Second generation 60 per cent cana 



Lamarckiana 



Lamarckiana 



Lamarckiana 



Lamarckiana 



1914 Third generation 46 per cent cana 



It is easily seen that they agree almost exactly with the pedigree 

 of mutant no. 1, and simply give further proofs of the conclusions 

 drawn from this. The size of the two cultures is given in table II. 



i) Excepting the case of biennials; see later statement. 



