48 BULLETIN 1111, U. S. DEPARTMENT OF AGRICULTURE. 
tendency to mixing and degeneration of varieties. But this tendency 
may be counteracted by organizing one-variety communities. 
Though larger units are desirable, the practical minimum of 
organized production is the gin-unit community, to include all the 
farmers who take their cotton to the same gin. Separate ginning 
and isolation and roguing of seed fields is essential to organized 
effort for utilizing superior varieties of cotton. The mixing of 
different kinds of seed at the gins is the chief agency of deterioration 
of varieties, and must be avoided if other precautions are to be of 
practical value. 
Except for the deterioration that results from the mixing and the 
crossing of different sorts there is no basis of fact for the popular 
idea that varieties of cotton run out rapidly or need to be changed 
frequently. With precautions of isolation, careful selection and 
roguing of the seed fields, and separate ginning, a variety of cotton 
can be kept pure and uniform and grown for many years. Produc- 
tion should be stabilized by the continued use of standard varieties. 
New sorts should not be substituted until their superiority is defi- 
nitely shown and such seed supplies are available that whole com- 
munities can change at one time. It is wasteful of good seed to send 
it out to scattered individual farmers in mixed-variety communities 
where isolation and separate ginning are not provided. 
Numerous varieties of cotton are unnecessary and undesirable both 
for agricultural and for industrial reasons. The commercial prac- 
tices of introducing many new kinds or of renaming old varieties to 
meet popular demands are based on a misunderstanding of the facts 
and do not tend to improve production, but add to the mixture of 
the " gin-run " seed. 
Though many varieties of cotton have been bred and distributed 
by the United States Department of Agriculture, only those are 
being maintained and extended on a scale of commercial produc- 
tion that have been adopted and centralized in communities so as 
to provide larger supplies of pure seed. Experience of nearly two 
decades has shown that the breeding and distribution of seed of 
superior varieties, either by the United States Department of Agri- 
culture or by local or private efforts, does not result in any general 
improvement of production, because of the lack of any adequate 
system for developing and maintaining large supplies of pure seed. 
Studies of utilization and of seed-supply problems have shown no 
way to develop and maintain adequate supplies of pure seed of 
superior varieties and keep such seed supplies permanently available 
except in one-variety communities where the mixing of seed at the 
gins and the crossing of varieties in the fields are avoided. 
Experience of several years in one-variety communities estab- 
lished in irrigated valleys of the Southwestern States has demon- 
