UViiK Bulletin. 9 



eral appearance of partially and irregularly flattened thick-walled 

 tubes twisted into spirals. Often the walls of the fibers are solid, 

 partially or totally, in which instance their value is greatly reduced 

 for commercial purposes. The fibers are tolerably uniform until 

 about -f to fr of their length is reached, when they gradually taper 

 to \ to ^, their greatest diameter, and then abruptly end ; the 

 tapering portion of the fibers being usually cylindrical in form, with 

 a decidedl}^ strong tendency to a solid nature. It is the spiral char- 

 acter of the fibers and their resulting natural inclination to interlace 

 and interlock that so admirably fits cotton lint to spinning purposes, 

 for were the fibers devoid of this spiral form they would lie together 

 without possessing any or very little binding power. 



Lengthy Diameter, and Tensile Strength of Fibers. — ^Although 

 increasing the yield of any variety in any year through higher fer- 

 tilization of the same soil is generally accompanied by a slight short- 

 ening of the staple, yet the results recorded in Table II seem to indi- 

 cate very strongly that there is also an independent and potent influ- 

 ence exerted by season ; as, with tAvo slight individual exceptions at 

 Iredell, the fiber of the tw^elve varieties tested at both the Edgecombe 

 and Iredell farms averaged longer in 1904 by 2. .5 and 1.8 mm. 

 respectively than in 1905, irrespective of yield, which, however, were 

 not generally widely different in the two years. 



The average length of the fiber of upland cotton as represented 

 by these twelve varieties grown under North Carolina conditions, 

 was found to be 21.3 mm. (.84 inch) as a result of four hun- 

 dred and seventy-five measurements ; while the weight required to 

 break individual fibers (tensile strength) was 6.83 grams (.24 ounce). 

 As a result of over eighteen hundred measurements of the lint of 

 Eussell's Big Boll cotton from the crops of 1902, 1903, and 1904, 

 grown on the Edgecombe farm, it was found that the average length 

 of the fibers of this typical short staple variety was 20.9 mm. and the 

 diameter .0237 mm., while the average weight required to break 

 individual fibers was Y.12 grams, which figures are not materially 

 different from those given in Table II. 



As the average length of the fibers of this typical variety are 882 

 times that of their diameter, then were the diameter of the average 

 fiber magnified to one inch its leng-th would be an irregularly hollow 

 twisted tube TS^/o feet long. The w^eight of each fiber is, on an 

 average, .000003024 or -g-g-reTs gi'am, and as there are about 150,- 

 000,000 individual fibers in one pound of lint, the quantity in a 

 pound would reach 1,948 miles if the fibers were placed end to end. 



We have found, as an average of a considerable number of meas- 

 urements, that the fibers on the crown (small) end of the seed are 

 longer by .3 mm. than those on the butt end. It has also been 

 observed that on imperfect seed (one-third the size of mature seed) 

 the lint is about normal in length, but not in diameter and tensile 



