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 jDarental 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. 



