No. 557] PARTHENOGENESIS IN NICOTIAN A 287 



ful case of N. plumbaginifolia. The seed of this excep- 

 tion was secured in a field experiment conducted on the 

 heavy clay loam of western New York, used as a check 

 on the experiments of Professor East made on the light 

 sandy loam of eastern Massachusetts. Since the seed 

 from this one capsule of N. plumbaginifolia was all that 

 was obtained from ninety-eight emasculated blossoms of 

 this species, it is reasonable to treat it as the result of an 

 experimental error. 



The method of testing for parthenogenesis in these 

 field experiments consisted simply in emasculating and 

 covering the flowers. Both paper sacks and cotton bat- 

 ting were used to protect the stigmas from self or cross- 

 pollination. When the latter covering was used the 

 anthers were removed with the assistance of a small wire 

 hook which minimized the injury to the corolla and the 

 cotton wad was then fastened over the end of the corolla 

 tube with the aid of a rubber band. The supposed ad- 

 vantage of the cotton batting was that it would interfere 

 less with the photosynthesis processes, than the paper 

 sack, as it excludes much less air and sunlight. The seed 

 of N. plumhagini folia was obtained from a capsule 

 covered with the cotton batting: otherwise, no definite 

 results were noted in favor of either covering. As the 

 heavy rains and strong winds will break off the capsules 

 covered with cotton, it is advisable to enclose them with 

 netting sacks. 



The extent of these emasculation experiments of Pro- 

 fessor East and myself in which not a single seed was 

 produced outside of the capsule of N. plumbaginifolia 

 already noted, is already seen by referring to Table I. 



Mrs. R. H. Thomas was much more fortunate in her 

 emasculation work, as she obtained fertile seed with no 

 apparent difficulty. Why parthenogenetic tobacco seed 

 should develop so readily in England and so rarely, if 

 ever, in the eastern part of the United States is difficult 

 to understand. The explanation may be found in the 

 differences of the soils and the climatic conditions of the 



