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BIKANER WOOL AND ITS IMPROVEMENT [Vol. XXII, Part IV
Stretched fiber length measurements were made of the fiber types which were
separated out in the count analysis. Burns' improved technique [13] was used
for the measurements. One hundred fibers of each type were measured, except
when their total number in the sample was smaller.
Thickness measurements of each sample as a unit and of the fiber types after
separation were made separately. Duplicate composite samples were used in the
former case, while the fiber types that were used for the stretched fiber length
measurements were utilized in the latter case. The longitudinal short-section
method was used in the thickness measurements [1]. The minimum number of
readings to come within a prescribed limit of error was first worked out by the
formula employed by Roberts [28], and all measurements were made accordingly.
Only 100 readings were recorded to measure the fiber types.
The contour ratio, which expresses the ellipticity of the fiber cross section, was
measured in terms of the ratio of the major to the minor axis [31]. Barker [8]
has proved that in two wools of the same fineness, the more circular wool spins
better. Hardy's technique [19] was used in making the cross sections. The cross-
sectional fiber images were projected and photographed on sensitized bromide paper.
The major and minor axes of each fiber cross section were measured with the
bi-diameter scale and recorded. The contour ratio was worked out from these
readings.
The study of scale structure was made by obtaining surface impressions with
the aid of a thermoplastic film according to the technique developed by Hardy
and Plitt [20]. Until recent years, an efficient method for the study of scale struc-
ture had been a difficult problem, but the above method gives satisfactory results.
The impressions on the film were mounted on a glass slide and projected at a magni-
fication of 500 diameters. Photographs of projected images were then obtained
on sensitized paper, showing representative fibers for the different measurements.
The attributes studied were the scale outline, the number of scales per unit
length, the average visible scale height, the number of scales along the margin
per 100µ length, and the relationship of scale height to fiber diameter.
RESULTS AND DISCUSSION
Medullation Test
The results of modullation test both by fiber type analysis and cross-sectional
technique are presented in Table I. The fiber-count analysis reveals that the
average fiber type content in the 8 samples is 58.6 per cent true wool, 29.8 per cent
heterotype, 11.4 per cent hair, and 0.1 per cent kemp. The largest variation is
in the true wool fibers—from 16.8 per cent to 96.5 per cent; variation in the hetero-
typical fibers is from 3.5 per cent to 49.3 per cent, and in hair from 11.3 per cent
to 33.6 per cent. Four samples show total freedom from hair and 6 samples are
free from kemp. The average content of kemp fiber is only 0.1 per cent, which
may be considered negligible. No colored fibers were found in any of the 8 samples.
By the cross-sectional image method, the average percentage of non-medullat-
ed fibers is 70.7 per cent, and of medullated fibers 29.3 per cent. The range of