Descendenz u. Hybriden. 185 



Macdougal, D. T. (assisted by A. M. Vail, ö. H. Shull, J. K. Small), 



Mutants andHybrids of the Oenotheras. (Carnegie In- 

 stitution. Pubiication 24. p. 1— 57. Fig. 1 — 13. PI. 1—22. 1905.) 



As a result of the continued effort to establish the nativity 

 of Oenothera lamarckiana it has been fairly conclusively deter- 

 mined that it is a true and independent species, native to 

 North America, altough this conclusion has not been rea- 

 ched by Observation of living specimens in the field. At least 

 this species has remained unchanged for one hundred and 

 sixteen years. 



The material used under the name Oe. blennis, by de 

 Vries, proves to be what has been called Oe. blennis grancll- 

 flora. Oe. grandlflora Ait., has been rediscovered in a place 

 not far from the original locality, where Bartram collected it 

 in 1776. Oe. grandlflora Ait., Oe. lamarckiana Ser., and Oe. 

 argllllcola MacKenzie, appear to be much more closely related 

 to one another than to Oe. blennis. Cultures of Oenotheras 

 have shown that two or more elementary species have been 

 grouped under some of the specific names. This has been 

 especially observed in the case of Oe. blennis, one of the forms 

 of which appears to be in a mutating condition. Oe. criiclata 

 is composed of three elementary species, one of which also is 

 found to be mutating. 



The hybrid Oe. lamarckiana and Oe. criiclata is of a single 

 type with the characters of the pollen parent largely dominant. 

 The hybrid Oe. lamarckiana and Oe. blennis is pleiotypic, there 

 being four sharpely marked forms. One of these types evinced 

 a remarkable predisposition towards attack from a fungus pa- 

 rasite. Three of the types were goneoclinic to the pollen parent 

 while the fourth may be said to be intermediate. 



The recurrence of known mutants of Oe. lamarckiana was 

 observed and also the appearance of seven forms not definitely 

 assignable to any of these, was noted. The occurrence of these 

 perhaps new mutants, indicates that under the new conditions 

 of cultivation the mutating condition has been heigthened rather 

 than diminished. 



„The results of the Statistical studies show that some of the 

 unit-characters of the mutants have a much greater variability 

 than the corresponding features in the parent form, and the 

 greater amplitude of the fluctuations is coupled with a decreased 

 correlation." This greater variabiHty does not however seem 

 to result in, in any way bridging the gap between the mutant 

 and the parent form, the variability is not in the direction of 

 the parent type. H. M. Richards (New York). 



Proceedings International Conference on Plant Breeding and Hybridiza- 

 tion Horticultural Society of New York. Memoirs. Vol. I. 1902. 



The following are abstracts or titles, of the fourty odd papers 

 presented to the above Conference, during the sessions in New 

 York city on Sept. 10, Oct. 1 and Oct. 2 1902. 



