12 The Bulletin. 



During the time embraced in the comparison above, RusselFs 

 Big Boll has averaged the lowest percentage of lint to seed with 

 32.81 per cent, while Peterkin's Improved has stood highest with 

 39.57 per cent, an average excess of 6.76 per cent over Russell's Big 

 Boll. Per cent of lint, however, must not be confounded with that 

 most important factor of yield, for it has been found, as a result of 

 rather extended investigation with about forty varieties, that often 

 those varieties yielding the smallest or medium percentages of lint 

 are the ones that produce the largest number of pounds of lint per 

 cent, notwithstanding their small percentage yield of lint. In a 

 detailed study of Russell's Big Boll cotton during the past four or 

 five years, it has also been demonstrated that increasing the percent- 

 age of lint is generally naturally accompanied by a decrease in the 

 length of the lint and an increase in its diameter, which are charac- 

 teristics detracting somewhat from the commercial value of the lint. 



Effect of Location, Soil, etc., upon Percentage of Lint. — As shown 

 by Table III, the percentage of lint produced by the different varie- 

 ties during three consecutive years were, with two exceptions occurring 

 in 1903, always higher at Red Springs than in Edgecombe, while the 

 average results for the former locality were invariably higher than 

 those at the latter, the increase being 1.49 per cent with Russell's 

 Big Boll; 2.95 per cent with Culpepper's Improved; 1.76 per cent 

 with King's Improved, and 0.67 per cent with Peterkin's Improved. 

 That a more complete understanding of the results may be obtained, 

 it should be stated that these tests were conducted at Red Springs 

 on a coarse sandy soil possessing a sandy-cla^y subsoil at a depth of 

 12 to 15 inches, while in Edgecombe they were located on a soil con- 

 sisting of sandy loam, with moderately fine sand, underlaid by a 

 rather tenacious sandy-clay subsoil at a depth of 8 to 12 inches. It 

 would therefore seem that the variations observed between the per- 

 centages of lint by the same variety at the same farm in different 

 years will have to be largely accredited directly to differences in 

 yield due to more favorable conditions for growtli and development 

 that obtained in the soil. 



Effect of Field Selection of Seed upon Percentage and Length of 

 Lint. — In working with Russell's Big Boll variety during the past 

 three years, the effect of field selection of seed has been marked, as 

 the difference between the highest and lowest percentage of lint to 

 seed obtained in 1904 was 11.25 per cent; while that; started with 

 in 1902 on the parent samples was only 3.64 per cent. In the 

 length of staple, the difference between the shortest and longest fiber 

 was 1.2 mm. at starting, and in two generations the divergence had 

 increased to 11 mm. The per cent of lint to seed produced by the 

 progeny of one sample had been increased 6.46 per cent, while the 

 length of the staple of another had been increased 6,4 mm. within 

 two generations by selection. 



