330 



WILD AND CULTIVATED COTTONS 



Develop 



ment. 



selection (above briefly indicated) subsequently conducted until the 

 degree of fixity had been attained that justified their recognition as 

 new stocks, with such and such properties. These are the opinions 

 currently accepted by practical men. 



Mr. Herbert J. Webber has devoted much special study to the 

 science of cotton improvement by continuous and gradual selection. 

 His results have already been briefly indicated (see pp. 282-3) in 

 connection with Sea Island cotton, and need not be repeated here. 

 Standards. The principles involved are (a) increased weight of wool (lint) to weight 

 of seed : that is to say, the seed-cotton is weighed and subsequently 

 the proportion of ginned lint afforded is ascertained and registered. 

 An increase relatively of the yield of lint is a desirable criterion. 

 But (b) it is necessary to test the yield to the acre. That is to say, 

 the fibre to seed may be in a satisfactory proportion, but the number 

 of pods produced per plant abnormally low. These two points 

 satisfactorily established, the floss is next (c) tested as to uniformity 

 (see p. 27, 34-36 and 49-51), and also as to length, fineness, strength, 

 colour and softness (pp. 28, 41-44). Lastly (d) suitability to climate 

 and soil (pp. 30, 38, 47-9), season of cultivation (pp. 29, 30-33), also 

 liability or immunity to diseases or pests, has to be considered. 



It will be seen from the illustrations already furnished under the 

 headings of the species of plants, that expert cotton farmers have 

 established a most useful method of expressing by figures the relative 

 values of crops (see p. 283). 



Perhaps no better example could be given of the value of selection 

 and preservation of manifestations that appear suddenly as a method 

 of stock improvement than the results attained in the production of 

 disease-resistant forms. Mr. W. A. Orton reviewed the results 

 achieved in a paper delivered before the Conference on Hybridisation 

 of 1902. He there describes experiments carried out by the United 

 States Department of Agriculture in the Southern States with the 

 fungal disease known as ' Cotton Wilt.' The parasite in question has 

 been named Neocosmospora vasinfecta. It enters the tissue of the 

 cotton plant through the roots and grows upwards, invading the region 

 of the ascending sap and thus depriving the cotton of nourishment, 

 and causing the withering up and death of the superficial structures. 



The usual remedial measures, such as rotation of crops, the use of 

 fertilisers, and the employment of fungicides, having all proved 

 unavailing to check the disease, the discontinuance of cotton cultiva- 

 tion became almost inevitable in badly affected areas. Fortunately, 



Sudden 



manifes- 

 tations. 



Wilt. 



Remedies. 



