CROP-PLANTS 355 



the villages. Only one of this group has been developed as a major 

 crop. This is the Ishan cotton of Nigeria, which on trial with other 

 types of cotton was found to be resistant to a leaf-curl disease. 



One may say that the whole of the cotton production, with this 

 exception, has been developed from recently introduced seed of 

 the Upland American cotton G. hirsutum, as far as British depen- 

 dencies are concerned. The French have introduced varieties of 

 G. herbaceum and G. arboreum var. neglectum into the French Sudan, 

 and claim that these Old-World cottons are more suitable for the 

 drier regions than are varieties of G. hirsutum. 



The chain of experimental stations, some organized by and 

 others assisted by the Empire Cotton Growing Corporation, are 

 studying breeding, especially that of disease-resistant strains. The 

 Reports from Experimental Stations, published annually by the Cor- 

 poration, give full accounts of progress. Much of the work in Africa 

 has been directed towards simple selection combined with self- 

 pollination, but crosses have been sent from the Corporation's 

 central research station at Trinidad, where also cytological study 

 has furnished results of fundamental importance in plant breeding. 

 The only other crop-plants on which the empirical results of experi- 

 ment have been checked by cytological studies in Africa appear 

 to be sisal and coffee, on which fundamental studies are in progress 

 at Amani. 



It has been suggested that some of the work on cotton has failed 

 because useful types, which have been selected for one set of con- 

 ditions, have not maintained these characters when transplanted 

 to different conditions, but on the whole remarkable results are 

 forthcoming. To consider first the introduced American strains of 

 cotton, the Empire Cotton Growing Corporation's station at 

 Barberton in the Union has shown the extreme value of the newly 

 developed jassid resistant cotton known as U.4., strains of which 

 are now in general use in the Union, Southern Rhodesia, and 

 Nyasaland, and are competing with local selections in parts of 

 Tanganyika and Uganda. Selection work with the various strains 

 is still continuing. At Barberton crosses of U.4. with Cambodia have 

 been made, and early and late strains have been compared. At 

 Gatooma in Southern Rhodesia the present standard strains are 

 being selected for jassid resistance; it is thought probable that 



