MUTANTS AND HYBRIDS OF THE OENOTHERAS. 3! 



have germinated first, as the seeds are very easily awakened from the 

 dormant condition, and a half dozen of these would have been trans- 

 planted to small pots by the gardener and the remainder would have 

 been destroyed in accordance with the usual custom. A still further 

 possibility lies in the fact that ordinary seeds are sown in mixtures of 

 potting soil that has not been sterilized, and might have contained 

 some seeds of this species from the cultures made in the New York 

 Botanical Garden for the previous year. 



The chief purpose of the earlier studies of the senior author of the 

 present paper was to make comparative studies of the parent-form with 

 its mutant derivatives, and also to test the stability of all of the types 

 concerned when cultivated under climatic conditions widely different 

 from those under which the mutants arose. Previously to the cul- 

 tures of 1904 less than a dozen of the various forms were brought to 

 maturity, and no attention was given to the possible occurrence of 

 mutants among the seedlings, although many might have been present. 

 Thus De Vries found 600 mutants in 50,000 seedlings from lamarckiana, 

 although he has pointed out that it would be possible to have exten- 

 sive plantations of seedlings which included no divergent forms. 

 Still another factor in the matter consisted in the inexperience of the 

 experimenter. The discovery of the mutants in the seedling stage 

 when only two or three small leaves are present is difficult for the first 

 time, although after becoming accustomed to the typical forms and 

 learning the aspect of the things to be looked for it is compara- 

 tively easy to recognize the better-known mutant types. Even then 

 the mutants previously seen are much more readily distinguished than 

 those known only by descriptions. This matter of practical observa- 

 tion depends greatly upon the plain mechanical fact that the selection 

 of the various forms is generally done in the seed-pans in which ger- 

 mination occurred in order to save the labor necessary in transplanting 

 them to small pots. 



After the major ends of the cultures had been reached in the 

 summer of 1904, and the newly-grown crops of seed were nearly 

 mature, the chances of losing any of the forms under cultivation by 

 accident was reduced to a minimum, and all of the seeds remaining on 

 hand were sown in pans of sterilized soil in order to make separate 

 observations upon the occurrence of mutants. Several thousands of 

 seeds of 0. lamarckiana of the crop of 1901 from the botanical garden 

 of Amsterdam, and of the same species of the crop of 1903 from the New 

 York Botanical Garden, were germinated in the above manner. In 

 addition, a few hundred seeds of 0. gigas o f the crop of 1903 from the 

 botanical garden of Amsterdam were sown 



