4 MUTATIVE EEVERSIONS IN COTTON. 



Reversions may be called total or complete when there are changes 

 of whole series of characters of parent varieties. 



REVERSIONS SIMILAR TO MUTATIONS. 



Wliether wild species originate by sudden mutative variations or 

 not, there can be no doubt in the case of the cotton plant that definite 

 variations occur and that they can give rise to new cultivated varieties. 

 The great majority of such variations are not preserved because they 

 are inferior to existing types. In a uniform, big-boUed type of cotton,, 

 such as the Triumph, many small-boiled individuals with different 

 habits of growth and other peculiarities may suddenly appear." 



In dilute hybrid stocks of Egyptian cotton, with only a small pro- 

 portion of Upland or Hindi blood, individual plants of apparently 

 "pure" Upland or Hindi cotton are found, while the other plants of 

 the same ancestry show only the usual Egyptian characters. If the 

 Egyptian parentage of these variations were not known it would not 

 be suspected from any of the characters that are brought into expres- 

 sion. If the experiments had been conducted on a smaller scale 

 and only the Upland or the Egyptian type had been familiar, these 

 changes of chaj^acters might have been looked upon as rare muta- 

 tions into new species, like those that occur in the garden variety of 

 the evening primrose studied by Professor De Vries in Holland. 



It does not seem probable that the niutative changes of characters 

 that often occur in cultivated stocks of cotton represent the attain- 

 ment of new characters, for the characters that come into expression 

 in this way are commonly found among the more primitive types of 

 cotton. Even the characters that have received the largest amount 

 of selective "improvement" from breeders, such as large bolls and 

 long, strong lint, have been found to exist in equal or greater degree 

 in related types of cotton that have been cultivated only in tropical 

 America without any conscious methodical selection by the Indians. 



The more degenerate variations of the Upland cotton, with very 

 small bolls and very shortlint, are inferior to any of the varieties 

 cultivated in the United States, so that they can not be looked upon 

 as results of crossing with other varieties, except as crossing may 

 be supposed to induce reversions. It is not necessar}^ to suppose 

 that these inferior characters are new, for some of them are closely 

 paralleled among the very diverse forms shown by the Kekchi and 

 other primitive Upland types that have been introduced from tropical 

 America and acclimatized in the United States in the last few years. 



Several of these newly introduced varieties also share the same 

 characters that render the Hindi variations of the Egyptian cotton 

 so strikingly different from the typical Egyptian plants, such as the 



« Local Adjustment of Cotton Varieties, bulletin 159, Bureau of Plant Industry, 

 U. S. Dept. of Agriculture, 1909, p. 17. 

 [Cir. 53] 



