lO MUTATIONS, VARIATIONS, AND RELATIONSHIPS OF THE OENOTHERAS. 



frequency of the derivatives. No proof has been produced to show that the 

 frequency of mutations might be increased beyond the Hmit of 5 per cent 

 found by De Vries, but it is a well-known fact that mutations of all kinds may 

 be decreased by inadequate nutrition, and it is quite possible that the parental 

 plants grown to furnish seeds did not have the care and nourishment of pedi- 

 greed individuals used in the cultures. The appearance of the rare ruhrinervis 

 in the culture might be due to a hybridization with that form, since no evi- 

 dence has been offered to show that the fertilizations were guarded. 



The five cultures described together furnished albida, nanella, oblonga, lata, 

 gigas, scintillans, and nine other forms not positively identifiable at this time. 

 Seeds have been preserved, however, and it is hoped we may be able to 

 present descriptions of at least some of the forms at the close of another year. 



Since these cultures were carried through, De Vries has published the 

 results of his cultures from seeds obtained from seed merchants. 2000 plantlets 

 from seeds obtained from Haage & Schmidt of Erfurt contained i specimen 

 of ruhrinervis, which arises but rarely in any culture, i of oblonga, and 3 of 

 nanella. 



Two cultures were made from seeds furnished by Vilmorin and grown in 

 1 898- 1 899. The first gave 14 nanella, 3 lata, 3 scintillans, 1 albida, i oblonga, 

 and a few other divergent forms in 3500 seedlings. A second test yielded 

 3 lata, I nanella, and i ruhrinervis (?) in 600 seedlings. In both cases the pro- 

 portion of the mutants was not above 5 per cent, and was even less than that 

 described above (De Vries, 1905). 



In view of the numerous observations described above upon material from 

 the most widely separated sources, which show mutability, suggestions that 

 the mutability of Lamarck's evening-primrose has been consequent upon 

 its segregation in the Amsterdam Botanical Garden may no longer be taken 

 seriously, although no doubt the well-worn phrase will be duly rehearsed 

 from time to time by careless critics. 0. lamarckiana may be of hybrid origin, 

 and what species may not be; but if so this origin is not recent, nor can 

 sufiicient time be found to hunt down all of the unprofitable alternatives that 

 are offered for consideration. 



Exact records have already been made of lamarckiana, ruhrinervis, nanella, 

 and gigas in previous papers (MacDougal, Vail, Shull & Small, 1903 and 

 1904), and below are the principal taxonomic characters of albida, oblonga, 

 scintillans, hrevistylis, and lata, by which systematic descriptions of 9 of the 

 15 mutant derivatives iteratively yielded by lamarckiana are afforded from 

 material grown in New York (see plate i). 



Note. — The illustrations of 0. lamarckiana and O. ruhrinervis prcvionsly published by 

 MacDougal (1903) were reduced without proper indication of the scale. 



The capsule of 0. gigas is incorrectly given in another paper as 2 nun. in length when it 

 should be 2 cm. (MacDougal, Vail, Shull & Small, 1905.) 



