No. 547] GENETIC AL STUDIES ON (ENOTHERA 



:!83 



University for the facilities that have made possible 

 these studies. 



1. Methods 



The methods of culture were the same as those of the 

 previous season (Davis, '11, p. 196). I have, however, 

 adopted the system of collecting and sowing seed capsule 

 by capsule as being the safest way of regulating the 

 size of the cultures and obtaining a lair average of 

 results both ijiialitative and ijiiantitntive. Furthermore 

 the seeds which go into a seed pan are counted so there 

 is obtained some data on the percentage of germinations. 

 The count can not be made strictly accurate, for there are 

 in (Enotliera varying proportions of obviously abortive 

 seeds which so grade into seed of questionable fertility 

 that good and bad could not be separated unless dis- 

 sected. Nevertheless, these counts are important, espe- 

 cially in cases where it is fundamental that all fertile 

 seed be germinated, as in the comparison of reciprocal 

 crosses. 



(Enothera Lamarckiana 



The experience of the writer during the past six years 

 has forced upon his attention the fact that there is a wide 

 range in the bud and flower measurements of (Enothera 

 Lamarckiana in cultures that are practically indistin- 

 guishable as to their vegetative characters. 



De Vries in his "analytical table of flowers, fruits and 

 seeds" ("The Mutation Theory," Vol. I, p. 452, 1909) 

 gives the measurements of the petals of Lamarckiana, on 

 the average, as ,') 4 mi. long. 1 am growing strains or 

 biotypes of Lamarckiana derived fromseedsof De Vries 

 in which the petals measure from 4-4.5 cm. in length and 

 similar strains have been sent tome from Kngland, where 



biennis var. grandiflora. These very beautiful plants 

 constitute a sort of elite race and apparently represent 



