464 THE AMERICAN NATURALIST [Vol. XL VI 



During the summer of 1909 the seed produced by the 

 living plants was saved from each strain separately. In 

 the spring of 1910 a sowing was made of the original seed 

 that had sown the first nursery, which had been desig- 

 nated as nursery A. This sowing was known as 

 series 201. In addition another sowing was made in 

 1910, known as series 202, from the seed collected 

 from nursery A in 1909. This sowing was from seed se- 

 cured from plants that had survived the severe winter of 

 1908-09. In addition a number of rows were sown with 

 seed from nursery A plants, selfed during the summer of 

 1909. 



This second experiment, carried on by the writer, con- 

 sisted of a number of duplicate rows seeded (a) with seed 

 from original geographical sources, and (b) rows seeded 

 with daughter seed obtained from the plants surviving 

 the winter of 1908-09. These two seedings comprised 

 112 150-foot rows, each row containing up to 150 plants. 

 During the summer of 1910 the rows were thinned and 

 accurate countings were made. In the spring of 1911, 

 after growth was well started, a determination was made 

 of the number of dead plants, and in addition the living 

 plants were gauged as to their vigor, on a basis of 1 to 10, 

 the best plants receiving the highest markings. 



The data obtained indicated the apparent increase of 

 hardiness among the different strains. A possible 

 source of error was the effect of vicinism in nursery A 

 in producing hardiness in the progeny plants constitut- 

 ing series 202. Limited space prevents presenting the 

 evidence which would lead one to think that this error 

 was slight in effect and probably nearly negligible. 



Only a brief summary of the results can be presented 

 in this article, a detailed account of which must be left 

 to a future publication. In the first place, let us regard 

 the comparative results of the winters of 1908-09 and 

 1910-11 upon the strains in nursery A, and upon those 

 of series 201. These two sowings were from the same 

 lot of seed, and had they been representative samples one 



