32 HINDI COTTON IN EGYPT. 



The habit of these j^hints was much like the Cochin China parent and 

 also closely similar to that of the Rabinal and Pachon varieties of 

 Upland cotton from Central America. The plants were very hairy 

 and the bracts were unusually well closed, as well or better than in 

 the Rabinal cotton, and being also larger they remained closed to a 

 more advanced stage. This character of the closed bracts was also 

 shown among the hybrids. It was full}' expressed, or even intensi- 

 fied, in some of the plants that had yellow flowers and other unmis- 

 takable evidences of hvbriditv. AVell-closed hairv bracts have value 

 as a weevil-resistant character, since they exclude the insects from 

 the young buds.** 



The phenomenon of coherence of characters is not only of interest 

 from the standpoint of the scientific study of heredity, but is of 

 distinct practical importance in relation to the problem of develop- 

 ing and maintaining uniformity in cultivated varieties. It repre- 

 sents on the one hand a limitation of the power of the breeder to 

 make free combinations of the characters of different species, as in 

 ordinary Mendelian hybrids, but on the other hand it assists in main- 

 taining the uniformity of established strains and guarding them 

 against contamination. If there were no coherence in the expres- 

 sion of the characters any Hindi character could come into expres- 

 sion independent of any other. The work of selection would involve 

 a detailed inspection of each plant by all of its characters and would 

 require an amount of time that would make it entirely impracticable 

 as a farm operation, even though the farmer should acquire the neces- 

 sary skill. In short, it is the fact of coherence of characters that 

 lends value to selection, that makes it possible by roguing to improve 

 or maintain the qualit}- of the crop. 



The success of the Egj'ptian method of securing commercial uni- 

 formity by matching the color of the fiber rests also on the fact that 

 variations in the color of the lint are not independent of other char- 

 acters. The inferior lint of the Hindi plants and hybrids does not 

 have the same color as the lint of Eg}'ptian plants. If there were 

 no coherence of the Hindi characters the brown color would be found 

 in combination with the naked seeds and short lint of the Hindi type, 

 but this seems never to occur. 



Recognition of the principle of coherence calls attention to the 

 practical fact that plants seldom make serious changes in the expres- 

 sion of one character without showing changes of expression on other 

 characters. The plants that produce the inferior lint in the fall are 

 those that have departed from the regular courses of development 

 earlier in the season. Indeed, these departures from normal heredity 



"Weevil-Resisting Adai)tiiti()ns of the Cotton I'lunt, Bulletin No. 88, Bureau 

 of Plant Industry, U. S. Dept. of Agriculture, 1906. 



210 



