RESULTS OF SELECTION WITH SELF-FERTILIZED CROPS 131 



As shown by the last column of the table, only two of the 

 thirteen pure lines gave lower average yields than the commer- 

 cial variety for the four-year period. They are Nos. 15 and 35. 



Among oat selections (Anonymous, 1919) which have proved 

 their practical value may be mentioned Iowa 103, Iowa 105, and 

 lowar, all of which are pure-line selections from Kherson. These 

 selections were made by Burnett at the Iowa experiment station. 



SELECTIONS IN OTHER SELF -FERTILIZED CROPS 



An exhaustive account of the work that has been done in 

 isolating and testing pure lines of self-fertilized crops would 

 alone make a large volume. In this somewhat brief treatment 

 only a few typical examples are chosen. 



The Iron cowpea (Orton, 1911), which is resistant to wilt, 

 is one of the notable examples of what has been accomplished 

 by the introduction of a promising variety. The isolation of 

 this form alone has produced thousands of dollars for the farmer. 

 M. A. C. Robust bean (Spragg, 1919), which is a selection out of 

 the ordinary navy bean, has proved to be very much superior 

 in yield to the commercial variety. At the Svalof Experiment 

 Station (Newman, 1912), in Sweden, progress has been made in 

 isolating pure lines of barley which possess superior brewing 

 qualities. 



These few examples show the value of selection as a means 

 of crop improvement. The effect of selection is to isolate the 

 more desirable types from the commercial variety. After this 

 has been accomplished, crossing may be resorted to as a method 

 of obtaining a variety which combines the desirable characters of 

 several strains. 



