ON ATAVISTIC VARIATION IN OENOTHERA 

 CRUCIATA. 



After Oenothera Lamarckiana had shown itself to be a very proper 

 material for the study of the mutations by which new species sud- 

 denly arise from old ones, I was naturally led to investigate whether 

 in other plants similar mutations might not be met with. For it is 

 clear that the phenomena shown by Lamarck's evening primrose are 

 of prevailing interest only if they may be taken as an instance of 

 a general rule. The other species of the same genus were of course 

 the first to receive attention. Most of these showed no signs of 

 being fit for a study along the same lines, while on the other hand 

 one, Oenothera cruciata, was found to be inconstant in the very cha- 

 racter to which it owes its name. At least the plant which is culti- 

 vated under this name in European botanical gardens is variable 

 in this regard. 



In proposing to bring the results of my experimental cultures 

 of this plant before the readers of this journal, my aim is principally 

 to direct their attention to any deviations which the species of the 

 above-named genus might show in their native localities. For it 

 is of undoubted interest to the study of mutability to know whether 

 the variability which Oenothera cruciata displays with us is also met 

 with in America, in those parts where the plant grows wild. The 

 allied forms, such as 0. biennis and 0. muricata, should be tested 

 in the same direction. Any deviations from the original types should 

 be carefully observed and if possible perpetuated by seeds. Wherever 

 such deviations are found the question would have to be answered 

 whether the general type of the locality possesses the power of again 

 producing this deviation, and perhaps others too, in succeeding years. 



Oenothera cruciata Nutt. or Onagra cruciata (Nutt.) Small, as it 

 is also called, has been described and figured in Britton and Brown's 

 "Illustrated Flora of the Northern United States, Canada and the 

 British Possessions" (2:485. 1897). It is a rare plant, found wild 

 from Vermont to New York and Massachusetts, and ascends to 

 2,000 feet in the Xdirondacks. It is described as being annual and 

 flowering from August to October. It may readily be recognized, 

 even without flowers, by the narrowly oblong or oblanceolate leaves 



