CHANGES IN LIFE PEEIOD. 19 



Based on the data from the Arhngton Experimental Farm, the 

 varieties may be classified into seven groups according to their life 

 periods: 



Very early Maturing in 80 to 90 days. 



Early Maturing in 90 to 100 clays. 



Medium early Maturing in 100 to 110 days. 



Medium Maturing in 110 to 120 days. 



Medium late Maturing in 120 to 130 days. 



Late Maturing in 130 to 150 days. 



Very late More than 150 days. 



CHANGES IN LIFE PERIOD. 



Ball, in Bulletin 98 of the Bureau of Plant Industry, page 8, cites 

 the case of Agrostology No. 1299 (S. P. I. No. 17276), obtained from 

 France in 1902, as illustrating that a variety may progressively 

 change from early to late. According to Ball's records, this variety 

 matured at the Arlington Experimental Farm in 1902 in 95 days; 

 in 1903, in 120 days; in 1905, in 130 days. On the other hand, at 

 Knoxville, Tenn., the record of this variety is perfectly consistent 

 from year to year and it matures with the Buckshot, a very early 

 variety.** Planted August 2, 1906, both matured in 70 days; planted 

 May 25, 1907, both matured in 91 days; planted July 11, 1907, both 

 matured in 81 days; planted July 30, 1907, both matured in 84 days; 

 planted May 13, 1908, both matured in 80 days; planted July 17, 

 1908, both matured in 82 days. 



No. 1299 was not grown at the Arlington Experimental Farm after 

 1905 until 1909, when seed was obtained from the Tennessee Agri- 

 cultural Experiment Station. In this year it matured in 100 days, 

 exactly the same as required for Buckshot that had been grown con- 

 tinuously at Arlington. 



It seems difficult to reconcile these results with those reported by 

 Ball, but the subject needs further investigation. 



In the case of the Ogemaw variety, phenomena have occurred that 

 are precisely like those reported by Ball. As shown by Table III, 

 this variety required the following periods to mature at the Arlington 

 Experimental Farm: In 1905, 88 days; in 1907, 102 days; in 1908, 

 105 days; in 1909, 112 days. In all these years the variety remained 

 perfectly uniform and no variants have ever been found in it. In 

 1909 seed of this variety was secured from several sources to see if 

 any changes in its life period, which was suspected from its increasing 

 lateness at Arlington, had actually occurred. The results are shown 

 in Table IV. All of these lots of the Ogemaw variety came from the 

 same original source, namely, Mr. E. E. Evans, West Branch, Mich. 



a Bulletin 82, Tennessee Agricultural Experiment Station, p. 81, 1908. 

 197 



