4 BULLETIN" 38, U. S. DEPARTMENT OF AGRICULTURE. 
quality of the fiber, which more nearly resembles that of the Egyp- 
tian Jannovitch. Other promising types have since been developed 
in Arizona by the Department of Agriculture and are being tested in 
comparison with the Yuma variety. 
The methods used in this plant-breeding work are simple. In the 
first planting of imported seed every individual plant was examined'. 
The productiveness, earliness, habit of growth, and size of the bolls 
were noted, and the lint was combed out on the seed, measured, and 
pulled to test its strength. The best individuals were then selected 
and the seed from each was saved separately. In the following year 
the seed from each selection was planted in a " progeny row," the 
rows being side by side and of equal length. It now became possible 
to compare the different selections on the basis of the uniformity and 
desirability of their progeny and to discard rows in which the plants 
showed much variation or were for the most part inferior. All 
plants in the superior rows were then compared, the best individuals 
were selected, and their seed was planted in progeny rows the follow- 
ing spring. 
This procedure has been repeated each year. When a strikingly 
superior progeny row, such as that from which the Yuma variety 
originated, is discovered, an isolated field is planted with the seed 
and the inferior and off-type plants are rogued out before they come 
into blossom. By repeating this process of roguing several years in 
succession a high degree of uniformity is attained. 
HOW THE FARMER MAY KEEP HIS SEED PURE. 
Thus far we have been discussing the work of the plant breeder in 
producing new strains and varieties. No less important, however, 
is the maintenance of a variety after it has been developed, and here 
the cooperation of the grower is necessary. Take, for example, the 
Yuma variety, which is now being grown in the Salt River Valley. 
The grower should become thoroughly acquainted with the appear- 
ance of the plants, so that he may learn to recognize the characters of 
the leaves, bracts, and bolls which belong to typical Yuma cotton. 
This can scarcely be clone by reading a printed description, but when 
the characters have been pointed out by a person who is familiar with 
them they are not likely to be forgotten. With this knowledge well 
in mind, the farmer should then go over the field from which he 
expects to save seed for next year's planting and should rogue out 
every plant which strikes him as not typical. The work had better be 
done before the plants begin to blossom, so as to avoid contamina- 
tion of the good plants with pollen from the bad ones. A second 
rcguing when the bolls begin to set is also advisable in order to re- 
move any untypical plants that may have been overlooked the first 
