IMPROVEMENT BY SELECTION. 45 



series of plots, have nails driven 4 inches apart on their inner edges, 

 and the movable board has marks 4 inches apart across its front edge. 

 When one row is jjlanted the board is moved forward 4 inches to the 

 next pair of nails. The series when planted appears as in figure 13. 

 The dark circles represent plants which are to be removed imme- 

 diately before harvest, as those shown on the border adjacent to the 

 alleys have a larger food supply than those in the interior of the plot, 

 and must therefore be removed before choosing the best ripe plants. 

 Every individual plant has its number, and whatever notes are made 

 concerning it are entered under that number. Alleys a foot or more 

 in width are left between the series of plots that attendants may 

 have a place to walk in planting, weeding, and harvesting the plants. 



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Fio. 13.— Scheme of planting wheat in field crop nursery. Light circles represent plants of the 

 variety under experimentation. Dark circles represent another kind of wheat separating the 

 plots from the alleys, or from each other. 



Where a small number of plants is placed in a plot, this is separated 

 from the adjacent plot of the series by a different variety of wheat, 

 as shown by tlie rows of dark circles crossing the lower series in figure 

 13. Great care is used in preparing the plot to have the soil uniform, 

 and to so ari-ange the ditches in the alleys that surface water will not 

 run over the plots. T\w weeds are ivcpt carefully removed by hand, 

 and early in the season the soil is kept loose by stirring it with a very 

 small hand hoe. 



A new machine has recently been devised by the Minnesota experi- 

 ment station for doing this planting. One to three seeds are planted 

 in each hill, and when a few inclies higli all the plants but one per hill 

 are destroyed. It is used for other crops also. 



