MUTATIONS, VARIATIONS, AND RELATIONSHIPS OF THE OENOTHERAS. 79 



Thus of the great number of mutant individuals originated by 0. lamarck- 

 iana but few have been ruhrinervis, still a smaller number represented gigas, 

 while the combined observations at New York and Amsterdam have failed to 

 bring hrevistylis within the range of the cultures, this form having arisen at 

 Hilversum, where it is still in existence. To secure mutants, or to allow a 

 species to display its possible derivatives, the long stretch of centuries may be 

 shortened and as many individuals examined in a seedling stage in a single 

 season as might naturally mature in twenty decades. The real point to be 

 attained is to secure sufhcient individuals to include the proportionate num- 

 ber of all the derivatives. 



ADDITIONAL EVIDENCE AS TO THE DISTRIBUTION AND OCCURRENCE 



OF LAMARCK'S EVENING-PRIMROSE. 



The records and material cited and examined show that a large-flowered 

 evening-primrose, which can be identified with nothing so closely as with 

 0. lamarckiana, had found its way into the gardens near Haarlem, Holland, as 

 early as 1756, several years before 0. grandiflora was brought from its habitat 

 in Alabama to England in 1778. Also that an evening-primrose with large 

 flowers was seen on the sand banks north of Liverpool, England, in 1806, on 

 the coast of Somerset in 1837, and has been cited and described by various 

 authors in 1845, 1851, 1855, i860, and continuously since 1892. Plants 

 grown from seeds obtained from the region in question proved to be 0. lamarck- 

 iana with two of its mutants, rubrincrvis and lata. Not only did this con- 

 firm the supposition as to the long history of lamarckiana, but it also showed 

 that rubrincrvis had successfully maintained itself in competition with the 

 parental form, while lata had become capable of self-fertilization, the only 

 instance on record. 



THE MUTANTS AND MUTABILITY OF LAMARCK'S EVENING-PRIMROSE. 



The observations begun by De Vries upon 0. lamarckiana in 1884 and 

 continued upon purely pedigreed material by himself until the present time, 

 and the cultural experiments described in this paper, demonstrated a very 

 high frequency of mutation in this species and also that the mutative depart- 

 ures show a great diversity when compared with other forms. In addition to 

 the derivatives which constitute the greater proportion of the atypic offspring 

 gigas has recently reappeared in an example in New York, being one of the 

 rarer forms. Then the sudden appearance of a totally new type among the 

 mutants leads at once to the confirmation of the suggestion that certain 

 mutants may appear so infrequently that they might not be expected more 

 than once in a million individuals and consequently would not be seen except 

 at long intervals. 



Of the known mutants alhida, oblonga, gigas, nanella, lata, and scintillans 

 were found in the pedigreed cultures described in this paper, and with greatly 



