KRITISCHE BETRACHTUNGEN DER LAETA-VELUTINA-SPALTUNC 339 



zigjährigen Bestrebungen, vor allem die Variabilität der Oenothera so 

 sonderbar und eigenartig wie möglich zu machen, ist es kein Tag zu 

 früh, die Arten dieser Gattung einer eingehenden faktoriellen Analyse 

 zu unterziehen. 



SUMMARY. 



Examples taken from, the works of Renner and de Vries show 

 that different workers have classified the types obtained from crosses 

 between the species of Oenothera in different ways. Consequently, 

 different conclusions are arrived at. The naming of certain extreme 

 types has been the all important point, and various characters have 

 been put together in these types to fit the different theories. 



The importance of the segregation in Fi which separates the off- 

 spring in two types, laeta and vehitina (or analogous), has been over- 

 valued, while other segregating characters have been disregarded. This 

 explains why Renner distinguishes between complex characters with 

 habitual and species-separating effects and simple, less important, 

 Mendelian characters, exactly in the same way as de Vries in his 

 »Mutationstheorie» distinguishes between specific and varietal 

 characters. 



The subsequent naming of the gametes by Renner inclined to 

 too great a generalization of the results. This is clearly seen both in 

 the analyses of the segregations and in the theoretical discussions. 

 The Ç-gamete in 0. biennis, according to Renner, should have the 

 complex character albicans. This is not the same as the small flower 

 character which is caused by a special Mendelian factor according 

 to him (I have called this factor B). Which are, then, the characters 

 caused by this important species-separating albicans complex? Renner 

 mentions only the white-nervedness. But 0. Lamarckiana has this 

 character already. From the fact that he is not able to mention any 

 other character caused by the albicans complex it follows that this 

 cannot be considered als allelomorphic with the laeta-velutina 

 differences in O. Lamarckiana but with the factor for red-nervedness 

 {R). It is consequently r, and these characters have nothing to do 

 with the laeta-ireliitina segregation. Such a confusion would have been 

 impossible if the grouping of the segregation in a factorial scheme 



