A CASE OF MENDELIAN INHERITANCE COMPLICATED BY 

 HETEROGAMETISM AND MUTATION IN OENOTHERA 



PRATINCOLA 1 



FRIEDA COBB 



University of Michigan, Ann Arbor, Michigan 

 Received June 21, 1920 



TABLE OF CONTENTS 



INTRODUCTION 1 



Hypothesis of heterogametism 2 



Equivalence, within strain C, of pollen of Oenothera pratincola f. typica and mut. latifolia. . 4 

 The F 3 and F 4 generations of the cross mut. formosa from strain E X mut. latifolia from 



strain C 5 



The FI and F 2 generations of the cross f . typica strain C X mut. formosa strain E 6 



The FI and F2 generations of the cross mut. formosa strain E X f . typica strain E 7 



The FI and F 2 generations of various crosses between f . typica M (the new Mendelian strain) 



and f . typica of strain C, f . typica of strain E, and mut. formosa 8 



Various pedigrees of plants used in crosses 9 



DISCUSSION 10 



SUMMARY 13 



LITERATURE CITED 15 



APPENDIX TABLES 15 



INTRODUCTION 



In the study of heredity in the genus Oenothera simple Mendelian results 

 are very rarely obtained. It is generally conceded that the unusual results 

 are due to the production, by a single morphologically uniform strain, of 

 gametes of more than one type. The explanations have been various. 

 The mutation hypothesis of DE VRIES is of course well known. It has not 

 been generally accepted, however, as originally proposed. MORGAN (1918) 

 and MULLER (1918) have suggested point mutation, followed by crossing 

 over, an explanation suggested by their work on Drosophila. MULLER 

 has worked out experimentally a balanced lethal stock of Drosophila in 

 which certain seemingly aberrant phenomena of the Oenotheras find a 

 parallel. To what extent the parallel affords an explanation we can not 

 judge until the genetic analysis of the Oenotheras has been carried further. 



1 Papers from the Department of Botany of the UNIVERSITY OF MICHIGAN, No. 181. 

 GFNETICS 6:1 Ja 1921 



458726 



