RESULTS OF SELECTION WITH SELF-FERTILIZED CROPS 119 



best seed on the spike would yield correspondingly the best plant. 

 Le Couteur and Shirreff placed all the emphasis on the original 

 plant selection, while Hallett believed he could improve the prog- 

 eny of an individual plant by further selection. Needless to say, 

 Hallett made no progress after the initial selection. A number of 

 his improved varieties were introduced and widely grown. 



Louis Leveque de Vilmorin formulated a breeding principle 

 as a result of a series of experiments performed by himself and 

 his father which was published in monograph form (1852). 

 These early studies were carried on with vegetables and the con- 

 clusion was reached that the only way to determine the breeding 

 value of a plant was to grow and examine its progeny. Much 

 study was made by the younger Vilmorin with the sugar beet. 

 This is not a self-fertilized plant, but the principles learned 

 have a direct bearing on selection with self -fertilized crops. In 

 the first few years the problem of determining the sugar content of 

 mother beets without injury to the roots received particular 

 attention. Weighing a small ingot of silver in the juice extracted 

 from a small piece of root was found to be an accurate method of 

 determining density and thus sugar content. Roots of similar 

 sugar content were then used as mother plants and their breeding 

 nature determined. Some gave progeny with high sugar content 

 without pronounced variability; other mother plants gave varia- 

 able progeny some of which were high in sugar content and others 

 much lower, while some mother beets produced progeny of such 

 inferior sugar content that all were immediately discarded. 

 Later the sugar content was determined by means of polarized 

 light (Babcock and Clausen, 1918). As an example of his 

 results may be mentioned a strain of beets which, after three 

 years' selection, gave juice with an average density of 1.087 

 while unselected seed grown in the same field gave an average 

 density of only 1.042. Andre Leveque de Vilmorin produced a 

 desirable cultivated form of carrot by three years of selection from 

 wild forms. Louis de Vilmorin also made a collection of wheats 

 and other grains from all parts of the world. After 50 years 

 of selection within isolated lines of wheat, no notable change 

 was observed (Hagedoorn, A. L. and A. C., 1914). 



Willet M. Hays, formerly of the Minnesota Experiment Station, 

 was the first in America to adopt the "Vilmorin method" 

 for small grains. In 1891 he introduced what is known as the 

 centgener method of grain breeding (Hays and Boss, 1899). 



