20 BULLETIN 1111, U. S. DEPARTMENT OF AGRICULTURE. 
action for cleaning out the mixed seed and then maintaining a pure 
stock. As long as isolation is maintained the varieties are preserved 
with no evidence of " running out " that has anywhere been estab- 
lished on a basis of scientific credence. The districts that produce 
the good seed do not change their varieties, but continue to furnish 
the same seed for those who believe that '* seed must be changed." 
The idea formerly entertained that cotton is not cross-pollinated 
or that crossing is very infrequent and not of practical importance 
in relation to seed supplies has proved to be erroneous. Although cot- 
ton pollen is not blown about by the winds, because the grains are 
sticky and adherent, the pollen is carried commonly for consider- 
able distances by bees or other insects that visit the flowers, so that 
varieties growing in neighboring fields are cross-pollinated, in addi- 
tion to the general crossing that takes place in fields where mixed 
seed is planted. 
Apart from the results of mixing and crossing, no real basis of 
natural law, reason, or necessity for the supposed rapid deterioration 
of seed or for the shipping of seed about from one district to another 
has been demonstrated in connection with cotton. After long periods 
of years it may be that varieties will deteriorate, decline in fertility, 
or become more susceptible to disease in spite of careful selection 
being applied, but at least it has to be recognized that such eventual 
deterioration, if the fact were established, would be quite distinct 
from the " running out " through the crossing and mongrelizing of 
different sorts that are grown and mixed together. 
Mongrelizing is a result of careless handling of varieties instead 
of being a defect or a disease. The supposed remedy, " changing the 
seed," does not remove the cause of degeneration, but only invites 
more " running out." The more numerous the varieties represented 
in a community, the greater the mixing of the seed at gins and cross- 
ing in the fields. Instead of " change of seed," the methods of obtain- 
ing the seed supply need to be changed, so that varieties can be pre- 
served and kept uniform instead of being mixed and allowed to 
deteriorate. No matter how good the original varieties may have 
been, a mixed stock becomes, in a few generations, thoroughly mis- 
cellaneous and mongrelized, with many abnormal and infertile 
plants, very inferior to the parental types. 
Once the belief in rapid " running out of varieties " is abandoned, 
the supposed need of a continual succession of new varieties may give 
place to a stable system of production, with no casual changing or 
mixing of varieties. A variety that is once established in cultivation 
should continue in use until a better is definitely known and adequate 
supplies of pure seed are provided in advance, so that whole com- 
munities at once may secure a new basis of production. 
