36 HINDI COTTON IN EGYPT. 



disease may be an unrecognized cause of much damage to the crop. 

 It appears that the symptoms are generally more pronounced on 

 land that had cotton the year before, but the observations have not 

 extended far enough to establish this point. 



RELATIONSHIPS OF HINDI AND EGYPTIAN COTTONS. 



The Egyptian cotton in the United States is exposed to the addi- 

 tional danger of crossing with the American Upland type of cotton. 

 It is quite as important to guard against this danger as to exclude the 

 Hindi contamination that has caused so many difficulties and losses 

 in Egypt. 



Experiments indicate that the result of allowing the Egyptian 

 cotton to be crossed with Upland pollen will be much the same as 

 with the Hindi, and this is also to be expected from the fact that 

 the Hindi cotton shares many of the characters of Upland cotton, 

 and especially those of some of the types of Upland cotton that have 

 been discovered recently in southern Mexico and Central America." 



Though diti'ering in minor details, there is a general agreement 

 between the American Upland types of cotton and the Hindi in the 

 habits of growth, the form, color, and textures of the leaves, in- 

 volucres, and flowers. The external characters of the bolls are also 

 much the same. The principal difference lies in the character of the 

 seeds. In the American Upland cottons the seeds are generally 

 covered with a dense coat of short fuzz, though some of our varie- 

 ties show frequent variations in the direction of naked seeds, like 

 those of the Hindi cotton. Indeed, there are occasional variations 

 where the lint and the fuzz are both lacking, showing that the seed 

 characters of the Hindi cotton lie within the range of variation of 

 the Upland type. Thus if the parentage of a hybrid plant is not 

 knoAvn it may be impossible to determine whether it represents the 

 Hindi contamination or an Upland cross. In general it may be 

 assumed that plants with hairy stems and leaves represent Upland 

 hybrids rather than Hindi, for the t3'pical Hindi cotton is not hairy. 

 Yet a few hairy Hindi-like plants have been found in Egypt as well 

 as in plantings of imported seed in Arizona. 



From the standpoint of the stud}' of heredity it would be very 

 desirable to determine when the Hindi contamination of the Egyp- 

 tian cotton took place. The Hindi variations may represent a recent 

 admixture or the crossing may have taken place so far back as to 

 represent a general constitutional tendency to reversion pervading 

 the whole Eg^'ptian type. The idea that the Hindi cotton grew as 

 a wild weed in Egypt would allow us to suppose that the process of 



" ()ri;,Mii of the Hindi Cotton, Ciirular No. 42, Bureau of Plant Industry, U. S. 

 Dept. of Agriculture. 

 210 



