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THE AMERICAN NATURALIST [Vol. XL VII 



from theory. For example, the geneticist is concerned, 

 if, under any of the conditions likely to obtain in his ex- 

 periments, plants ordinarily reproducing sexually should 

 be incited to reproduce parthenogenetically. 



This paper describes some facts on the subject ob- 

 tained by experiments on the genus Nicotiana.. 



The Material. 



The material used in the investigation was turned over 

 to me by Professor E. M. East, who had received it from 

 various parts of the world. Each species had been culti- 

 vated in pure lines for at least three generations, so that 

 it may be considered to be fairly well known. The spe- 

 cific names used are those accepted by Comes in his 

 "Monographic du genre Nicotiana," Naples, 1899. To 

 his descriptions, and to such figures as are published in 

 the Botanical Magazine, the plants corresponded per- 

 fectly. To all intents and purposes, therefore, the plants 

 may be considered wild, although they have been under 

 cultivation several years. 



The writer desires to express his thanks to Professor 

 East, under whose direction the investigation was car- 

 ried out, for the use of the pedigreed material and for 

 much valuable advice. Certain unpublished data ob- 

 tained in his own researches on Nicotiana are incorpo- 

 rated with his consent. 



Historical. 



For historical purposes it is only necessary to give a 

 brief review of Hans Winkler's paper, "Uber Partheno- 

 genesis und Apogamie im Pflanzenreiche," published in 

 1908; and the less comprehensive paper, "Partheno- 

 genese des Vegetaux Superieurs," of L. Blaringhem, 

 pnbli sited in 1909. Blaringhem in his historical account 



