MENDELIAN INHERITANCE IN OENOTHERA PRATINCOLA 13 



This paper records the case of a single unit character of the zygote, 

 revoluteness, determined by a complicated set of phenomena: an allelo- 

 morphic pair of factors (F and /), the dominance and recessiveness of 

 which produce no effect on the zygote except when the particular muta- 

 tional change from a to a has taken place; a mutation (a to a) occurring 

 repeatedly, but concealed, as long as self-pollination continues, by the 

 Mendelian factors FF, and Mendelian segregation concealed by matro- 

 clinic inheritance dependent on heterogametism (a and /3 gametes). It is 

 hoped that the case may help to throw light upon the seemingly peculiar 

 behavior of the Oenotheras. 



SUMMARY 



1. The male and female gametes of Oenothera pratincola are not alike. 

 Each zygote is formed by the union of an a (female) gamete and a (male) 

 gamete (except in rare cases which it is needless to mention here) and has 

 the constitution . It, in turn, produces a (female) and /3 (male) gametes. 



2. The a (female) gametes may undergo such mutation that, unless 

 certain factors for flatness are present, the resulting plants are revolute- 

 leaved. Such mutated gametes are designated a. 



3. The |8 (male) gametes have no such possibility of producing revolute- 

 leaved plants. 



4. Strain C carries in both male and female gametes, but not in the 

 characteristic a and |8 portions of the gametes, a freely segregating factor 

 for flatness (F), in the presence of which revoluteness can not occur, even 

 though the mutation to a has occurred. The constitution of f. typica 

 strain C is afiFF. 



5. Strain E does not carry in either male or female gametes the inde- 

 pendent factor for flatness which occurs in strain C, but its allelomorph 

 (/). The constitution of f. typica strain E is afiff. 



6. Mut. formosa, a revolute-leaved mutation thrown by strain E, differs 

 from f. typica strain E in that it contains a mutated a (a). The constitu- 

 tion of mut. formosa is a'Qff. 



7. There are two types of inheritance going on simultaneously and 

 independently in Oenothera pratincola, matroclinic inheritance, connected 

 with certain constant differences in factorial composition between male 

 and female gametes, and Mendelian inheritance, connected with an inde- 

 pendent segregation of factors carried by both gametes. 



8. The cross mut. formosa X strain C (afiff X aftFF) produces only 

 flat-leaved plants in the FI generation; in the F 2 generation there occurs 

 a Mendelian segregation in the ratio of 3 flat-leaved plants to 1 revolute 



GENETICS 6 : Ja 1921 



