ON THE OKIGIN AND BEHAVIOUR OF 

 OENOTHERA RUBRICALYX. 



By R. RUGGLES GATES, Ph.D., F.L.S., 



University of London. 



In a recent paper which purports to deal with F^ hybrids of 

 Oe. rubricalyx, Shull (1914) takes occasion to attack my conclusions 

 regarding the origin and hereditary behaviour of this mutant. I may 

 remark that I have been studying the hereditary behaviour of Oe. mut. 

 rubricalyx ever since it appeared in my cultures in 1907. The results 

 of these studies, portions of which have been published in several papers 

 (1909 — 1914), are perfectly clear and definite, and the main conclusions 

 to which they have led are, in my opinion, irrefutable. Among my 

 crossing experiments is an extensive series of ^i and F^ hybrids 

 be4;ween ruhricalyjc and Oe. grandiflora, Solander (Gates, 1914) num- 

 bering nearly 3000 plants. I have also gi'own a still more extensive 

 series of F-^ families, whose results confirm the previous conclusions 

 from the Fo, families and will be summarized in a book which is now 

 in press. 



Before entering further into the evidence on which my conclusions 

 rest, it may be well to examine for a moment the nature of the evidence 

 which Shull brings forward as the basis for his criticism and for con- 

 clusions which are contrary to mine. In the first place, the internal 

 evidence from the author's own paper, as well as other facts, shows that 

 his supposed pure rubricalyx was in reality Oe. rubricalyx x grandiflora. 

 This in itself of course vitiates in toto the " results " stated in his paper, 

 for in every cross mentioned one must read " rubricalyx x grandiflora" 

 instead of "rubricalyx." For example, when he describes what he states 

 is rubricalyx x rubrinervis F^ he is really describing (rubricalyx x g7-a7i- 

 diflora) x rubrinervis. What must one think of observations which 

 pretend to be critical, and yet which make the fundamental error of 



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