28 PLANT BREEDING. 



varieties, whicli are given by niniiher or name at the tops of the 

 lines. In each of the six sections there ai-e vertical lines representing 

 units of the various qualities. These run only through the range of 

 figures as given at the right ends of the lines, which include only the 

 variations in yield, in grade, or in other qualities in their respective 

 sections, and not the entire yield, etc. 



In section 1, at the right, the yields per acre are expressed in hush- 

 els of 60 pounds each, and since the yield is the qualitj' to which the 

 most value is attached, the new and also the old varieties are arranged 

 throughout the chart in the order of their yields. 



In section 2 the grades are expressed in percentages, thus making the 

 comparison of yield and grade comparatively easy in the two se6tions. 



In section 3 is given the relative rust resistance of tlie several varie- 

 ties, as expressed in percentages of rust showing on leaves and stems 

 during ripening. 



In section 4 is given the quality of gluten as determined by an 

 expert in stretching and manipulating the gluten from which the 

 starch had been washed out with cold water. (See PI. I, fig. 1.) 



In section 5 is given the percentage of dry glnten in the flour. 



In section (3 is given the quality of the flour as determined by the 

 bakers' sponge test (PI. I, fig. 2), expressed in the volume of loaf pro- 

 duced by each percentage unit of gluten. This is obtained by divid- 

 ing the grams of dry gluten in 100 grams of flour into the volume of 

 loaf of dough produced from the hundred grams of flour. Tliese 

 figures represent the averages between the volumes of the first and 

 second rise of each kind of flour. 



This chart is an aid in the selection of those varieties between 

 which hybrids are to be made. The new wheat known as Minnesota 

 No. 109 stands out j)rominently as the best wheat, and as one of the 

 parents to use for crossing to j)roduce further desirable variations 

 which may serve as foundations of new strains or varieties. Minne- 

 sota No. 163 is the next best yielder, has grain of good grade, is fair 

 in rust resistance (a point in which No. 169 is very strong), is good in 

 qualit}^ of gluten, verj^ good in the amount of gluten, faii- in amount 

 of loaf a given amount of gluten will make, and should serve well to 

 cross with the large-yielding No. 169. 



Minnesota No. 171 would also be a promising Avheat for liybridizing 

 with No. 169. No. 167, on the other liand, while nearly as large a 

 3'ielder as No. 171, is deficient in grade of grain and in the quality of 

 its gluten. Minnesota No. 149, though not so. large in yield as some 

 others, grades high on the market, has a relatively large amount of 

 gluten of very superior quality, and would rival No. 163 to hybridize 

 with No. 169. 



METHODS OF PLANT BREEDING. 



RELATION OF PLANT INTRODUCTION TO PLANT BREEDING. 



In addition to the limited number of native plants suitable to 

 special cultivation in each localitj^ every countiy finds it advanta- 

 geous to introduce plants from ()tlt<'i- countries, and to transfer plants 



