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THE AMERICAN NATURALIST [Vol. XL V 



student of genetics knows, come slowly, and the writer 

 feels no necessity of offering an apology in publishing 

 preliminary data, since they are based on three seasons' 

 study, even though he hopes to present more conclusive 

 evidence in the future. 



The cultures of the past season (1910) were grown 

 partly at the Bussey Institution and partly in the Botanic 

 Garden of Harvard University, where facilities were of- 

 fered for which the writer is deeply indebted. 



Methods 



To break the biennial habit and obtain flowering plants 

 in one season it is only necessary to sow seeds in the hot 

 house during the winter, where rosettes will develop, 

 which may be set out in the open in the early spring. 

 The cultures of 1910 were sown early in January and had 

 developed large rosettes by May 5, when the plants were 

 transferred to the gardens. It is best to sow the seeds 

 thinly in large seed pans (with, of course, sterilized soil) 

 from which each individual seedling may be potted. 



Cross pollination was always performed on flowers 

 from which the unopened anthers had been removed. 

 The best results are generally obtained when a castrated 

 flower is left bagged for twelve to twenty-four hours 

 before the pollen is applied, in order that the stigma 

 may have time to mature fully which will be evident from 

 the moist exudation on its surface. Strong manila bags 

 tied firmly over the pollinated flowers have proved 

 more satisfactory than special bags of paraffin paper, 

 which appear to hold the flowers in an atmosphere too 

 moist for the best results. It is my practise to dip the 

 forceps in a bottle of alcohol before each transfer of 

 pollen and also to rinse the hands in alcohol. The pollen 

 of Oenothera is so sticky that under ordinary conditions 

 there is no danger from wind blown pollen, and by fol- 

 lowing the practise outlined above there is little or no 

 probability of impure pollination. 



In the future my plan will be to sow the seed capsule 



