INTRODUCTION 291 
tenance of work already under way, Vilmorin undertook two projects 
which yielded results of the greatest importance to the entire world. 
One was the collection of wheats and other grains from many countries 
in order to compare them and to select those of greatest value. In con- 
nection with this work on grains he invented the pure-line method of 
selection and progeny test which came to be known as the ‘ Vilmorin 
Method” and which has been used so successfully with wheat and other 
self-fertilized plants. From our present knowledge of pure lines we 
can understand why this method was effective. Vilmorin’s other im- 
portant project was the improvement of the sugar beet. Previous to 
1850 the beets had been selected according to form only. This method 
of selection began as early as 1787 on the seed farm of H. Mette in Qued- 
linburg, Germany, according to Legier. Selection on the basis of specific 
gravity was practised from 1850 to 1862, when the method of determining 
sugar content by means of polarized light was introduced. His success 
made beet-sugar production a commercial possibility and gave his name 
an enduring place in history. 
More Recent Progress in Plant Breeding.—The great world move- 
ments of the 19th century following the improvement of transportation 
facilities, the migration of peoples, industrial development and the growth 
of international trade, together with the improvement of farm machinery, 
resulted in the extension of agricultural industries and gave a greater 
impetus to plant breeding. This activity was manifested first in Europe 
and later, particularly in the United States Department of Agriculture 
and the state experiment stations, in America. Naturally the efforts 
at improvement were concentrated in the main on the crop plants pro- 
ducing the raw materials of importance in the world’s markets, such 
as wheat and other small grains, sugar beets, corn, cotton, forage plants, 
the apple and other fruits. The methods employed were those which 
had been used in the past for the most part, but they were systematized 
and combined for more effective utilization. These methods may be 
classified under the following heads: 
1. Mass selection. 
2. Line selection and progeny test. 
3. Hybridization followed by direct utilization or selection and 
fixation of new varieties. 
4. Clonal selection. 
Mass Selection.—The method of mass selection consists simply in 
picking out choice plants from the main crop and sowing the seed from 
them en masse. It has long been used, especially in improving small 
grains, but it has also been used with many other crops. With this 
method it has usually been found necessary continually to repeat the 
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