NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
December, 1954 ]
B.
S.
GILL
251
METHODS
To cause complete disintegration and consequent release of oocysts from fæces
1 gm. of the latter was comminuted with 40 ml. tap water with the help of pestle
and mortar. The suspension was filtered through a strainer of (40 meshes/linear
inch) received in a glass bottle of 150 ml. capacity marked up to the level of 100 ml.
Enough water was added to bring the suspension to 100 ml. mark. A few (5-10)
glass beads were added to the bottle, and the latter shaken vigorously for 10 minutes
to form a homogeneous suspension. The suspension was then strained through a
fine mesh (100 meshes/linear inch) and the level again brought upto 100 ml. mark.
One ml. of the fæces preserved in potassium dichromate solution (series ' A ',
Table I) was washed free of the preservative, thoroughly shaken with glass beads,
strained and the volume made up to 100 ml.
One ml. of the homogenised suspension was poured into a centrifuge tube,
sufficient water added to bring it just up to the brim and centrifuged for two minutes
at 1200 r.p.m. Supernant fluid was sucked off without disturbing the sediment.
The chemical solution to be tried was added little by little while rotating the tube
between hands to affect thorough mixing, till the meniscus of the fluid in it rose
just over its brim. A coverslip was placed gently over it without entrapping any
air bubble and centrifuged as before. The cover slip was sharply lifted off between
the middle finger and thumb, placed on a glass slide and oocysts counted under the
low power of a microscope with the help of a veeder counter using Ehrlich's counting
eye piece (10 X) to squarely limit the field. A drop or so of the medium was added
to the centrifuge tube to bring the fluid upto its original level. Another coverslip
placed over it, centrifuged as before and the number of oocysts collected was
counted. This process was repeated till two trials successively failed to recover
any oocyst. The total number of oocysts recovered in this process is hereinafter
referred to as the ' primary recovery '.
The supernatant fluid was poured off and the sediment washed once with water.
The whole process outlined above was repeated with the second chemical solution
and oocysts recovered were counted. The third floating medium was tried on the
same sediment and the oocysts collected, if any, were counted. Total number of
oocysts counted in these two steps is hereinafter referred to as the ' subsequent
recovery '.
In order to ascertain the reliability of the three chemical solutions to give
consistent floats with the same suspension over and over again, six different fæcal
samples were used and with each sample three trials were conducted. The number
of oocysts recovered on the first centrifugation only were compared. Data on
these observations is embodied in Table II.
Data and its statistical significance
Tables showing the detailed manner of actual recovery affected by different
media and series of trials conducted are not included in this paper to economise
space, but they may be had from the Indian Council of Agricultural Research,
New Delhi. However, data have been summarily given in Table I.
252
FLOATING EFFICIENCY OF LEVITATING MEDIA [ Vol. XXIV, Part IV
TABLE I
Summary of the data relating to the actual recovery affected by media and the series of trials conducted
Trial No.
A
B
1st
4th
6th
7th
8th
3rd
2nd
5th
Sodium chloride solution
Primary recovery
No. of
oocysts
counted
593
111
232
581
615
559
234
112
No. of
centrifu-
gations
required
4
4
4
4
3
4
3
4
Subsequent recovery
No. of
oocysts
counted
1
2
1
1
2
3
0
0
No. of
centrifu-
gations
required
1
1
1
1
1
1
0
0
Zinc sulphate solution
Primary recovery
No. of
oocysts
counted
374
109
212
439
667
667
209
140
No. of
centrifu-
gations
required
3
4
4
4
4
4
3
3
Subsequent recovery
No. of
oocysts
counted
1
0
0
2
0
5
0
0
No. of
centrifu-
gations
required
1
0
0
2
0
5
0
0
Copper nitrate solution
Primary recovery
No. of
oocysts
counted
557
148
245
606
691
572
262
143
No. of
centrifu-
gations
required
3
3
3
3
3
4
3
3
Subsequent recovery
No. of
oocysts
counted
0
0
0
0
1
3
0
0
No. of
centrifu-
gations
required
0
0
0
0
1
1
1
..
NOTE.—Sediment left after primary treatment with ZnSO 4 solution was subsequently treated first with brine, and then with CuNO 3
solution for set A of trials ; the order of subsequent treatment was reversed for set B of trials ; the one left by brine (primary levitating
medium) was treated with ZnSO 4 and CuNO 3 solutions respectively for set A trials and CuNO 3 and ZnSO 4 solutions respectively for set B of
trials ; and residue left when CuNO 3 was used as primary medium was subsequently treated first with brine and then with ZnSO 4 solution for
set A of trials ; the order was reversed for set B of trials.
December, 1954 ]
B.
S.
GILL
253
TABLE II
RELIABILITY TESTS
Counts of first floats of three aliquots from the same fæcal sample
Sample No.
A
B
C
D
CuNO 3 solution
1st aliquot
301
505
391
184
2nd aliquot
310
535
415
166
3rd aliquot
284
540
401
210
Brine
1st aliquot
299
469
410
172
2nd aliquot
280
478
382
161
3rd aliquot
290
490
369
189
ZnSO 4 solution
1st aliquot
304
493
371
182
2nd aliquot
294
476
399
169
3rd aliquot
279
510
380
176
254
FLOATING EFFICIENCY OF LEVITATING MEDIA [ Vol. XXIV, Part IV,
The analysis of the numbers of oocysts floated with various chemical media
has been performed under the assumption that each and every fæcal sample of a
particular trial had contained the same number of oocysts. It was noted that the
numbers of centrifugations required to float the various numbers of oocysts in
different chemical media tried differed, to some extent from one another. It was
necessary, therefore, to examine the effect of the variable centrifugations and to
estimate the numbers of oocysts on equal numbers of centrifugations. The ad-
justed means and the significance of their differences are given in Table III. Other
results are incorporated in Tables IV, V and VI.
TABLE III
Adjusted mean numbers of oocysts in one trial
Chemical solutions
CuNO 3
Brine
ZnSO 4
Means
415.0
370.6
349.1
Significance of difference
No significant differences among the
adjusted means
TABLE IV
Number of centrifugations required to affect the total ' primary recovery '
Chemical solutions
Brine
ZnSO 3
CuNO 4
Means
3.7 (A)
3.6 (B)
3.1 (C)
Significance of difference
A vs. B=N.S.
B vs. C=S.
C vs. A=H.S.
S= Significant (0.051 P>0.01)
H.S.=Highly significant (P>0.01)
P.=Probability
TABLE V
Number of oocysts recovered at the first centrifugations
Chemical solutions
CuNO 3
Brine
ZnSO4
Means
358.9
(i.e. 84 per cent of the T.R.)
343.1
(i.e. 92.8 per cent of the T.R.)
(i.e. 90.8 per cent of the T.R.)
Significance of difference
No significant differences among
the means
T.R.=Total recently.
December, 1954 ]
B.
S.
GILL
255
TABLE VI
Means ' subsequent ' recovery for one trial
Chemical solutions
CuNO 3
Brine
ZnSO 4
Means
0.3
1.1
0.7
Significance of difference
No significant difference among the
means
DISCUSSION
The technique adopted was a simple modification of the Lane's [1923-24]
method. Concentration and flotation of oocysts were carried out in the same
tube. Both the steps were speeded by spinning.
No extra support in the form of horned centrifuge bucket [Lane, 1923-24] or
special clamp [Faust, et al., 1939] to be attached to the latter was needed. No
adhesive, as advised by Watson [1947] to glue the coverslip to the mouth of centrifuge
was required. Coverslip lifted off sharply removed all the oocysts sticking to its
undersurface. Coverslip of any specification served the purpose. No additional
apparatus was required. An ' all purpose ' centrifuge, a few centrifuge tubes with
perfect rims and grease-free coverslips were all the equipment needed.
Eight series of trials were conducted with CuNO 3 , ZnSO 4 and NaCl solutions.
Residue left by brine (as primary medium), in set A. (Table I) was levitated in
turn with ZnSO 4 and CuNO 3 solutions respectively, and the order of their
employment was reversed in set B. Thus each of the two subsequent media was
given equal chances to play upon the sediment left by the primary medium. The
same scheme, when other two solutions were used as primary media, was adhered
to as is evident from Table I. A careful scrutiny of the data has brought forth
the following conclusions :
1. That the CuNO 3 solution caused the highest concentration of oocysts in
75 per cent of the total trials, whereas each of the ZnSO 4 solution and
brine affected the greatest concentration of oocysts in 12.5 per cent
of the trials conducted.
2. That apparently, CuNO 3 solution floated a higher number of oocysts
than either brine or ZnSO 4 solution (adjusted means of the number of
oocysts floated in one trial being 415, 371 and 349 respectively) but
the differences in their floating capacities were not found to be statisti-
cally significant.
3. That CuNO 3 solution affected the statistically significant speediest
recovery of oocysts when used as a primary medium than either ZnSO 4
solution or brine. There was, however, no significant difference
between the rates of recovering oocysts with the latter two media,
December, 1954 ]
B.
S.
GILL
257
SUMMARY
Literature extant on the various techniques employed so far, for recovering
protozoal cysts from human and animal fæces has been briefly reviewed. Their
limitations and especially those of the procedures employed by workers on poultry
coccidia, have been pointed out. A simple, easy and yet very efficient modifica-
tion of Lane's [1923-24] D.C.F. technique for floating coccidia from fæces of poultry
has been described. Further, floating efficiencies of copper nitrate, zinc sulphate
and common salt solutions (aqueous) have been compared and their respective
merits discussed. Eight series of trials using a different fæcal sample each time
were conducted with both sporulated and unsporulated oocysts of coccidia. Data
thus obtained when submitted to detailed statistical analysis revealed that all the
three media were equally suited for the purpose except that CuNO 3 affected a
significantly speedier recovery than the other two media besides possessing a few
other advantages. This medium provided satisfactory visual facility, floated less
amount of debris and was not quickly crystallized thus making prolonged examina-
tion possible.
ACKNOWLEDGEMENT
The author wishes to place on record his sincere thanks to Dr H. N. Ray for the
valuable guidance and helpful criticism ; to the Indian Council of Agricultural
Research for the award of Research Fellowship ; and to Shri S. Sen of the Indian
Veterinary Research Institute, for helping in statistical analysis of the experimental
data.
REFERENCES
Andrews, J. and Tsuchiya, T. (1931). Poultry Sci., 10, 320
Beach, J. R. (1943). Cornell Vet., 23 ; 308
Farr, M. M. (1944). Poultry Sci., 23 ; 277
—
and Allen, R. W. (1942). J. Amer Vet. med. Ass., 100 : 47
—
and Luttermoser, G. W. (1941). J. Parasit., 41 : 43.
Faust, E. C., Antoni, J. S., Odom, V., Miller, M. J., Peres, R., Sawitz, W. Thomen, L. F., Tobie,
J., and Walker, J. H. (1938). Amer J. trop. Med., 18 : 169
Faust, E.C., Sawitz, W., Tobie, J., Odom, V., Peres, V. and Lincolme, D. (1939). J. Parasit., 25 :
241
Garcia, E. Y. and Pesigan, T. P. (1948). Univ. Philippines Nat. App. Sci. Bull., 7 : 299
Grumbles, L. C., Delaplane, G. P. and Higgins, T. C. (1948). Poultry Sci., 27 : 169
Koutz, F. R. (1948). Poultry Sci., 27 : 793
Lane, C. (1923). Trans. R. Soc. trop. Med., Hyg., 16 : 274
Lane, C. (1923-24). Ibid., 33 ; 521
Levine, P. P. (1939). Cornell Vet., 29 : 309
Morehouse, N. F. and Mayfield, O. J. (1945). J. Parasit., 32 : 20
Otto, G. F., Hewit, R. and Strahan, D. E. (1941). Amer J. Hyg., 33, D : 22
Ray, D. K. (1953). Proc. Zool. Soc. Bengal., 6 : 135
Ripson, C. A. and Herrick, C. A. (1945). J. Parasit., 31 : 99
Sheather, A. L. (1923a). J. Comp. Path. Therap., 36 : 71
Sheather, A. L. (1923b). Ibid ; 36 : 266
Swartzwelder, J. C. (1939). J. trop. Med. (Hyg.), 42 : 185
Watson, J. M. (1947). Ann. trap. Med. & Parasit., 41 : 43
Young, B. P. (1929). J. Parasit., 15 : 241
104 AR/54.
15
THE TECHNIQUE AND EVOLUTION OF THE CORE
TESTING METHOD OF SHRINKAGE ESTIMATION IN
WOOL IN THE U.S.A.
By GURBAX SINGH MAHAL and S. JAYARAMAN, Government Livestock Farm,
Hissar
(Received for publication on 30 April 1953)
(With Plates XIV-XV)
A CORRECT estimation of the yield (percentage of true wool content) in a consign-
ment of wool is of vital importance in the wool trade both for the buyer as well
as the seller. Wool, as is shorn from the body of the sheep, contains varying
amounts of extraneous substances such as grease, dried perspiration, sand, vegetable
matter, tags, etc. These substances are removed during scouring (washing) before
the wool goes into the manufacturing processes. Their removal results in a loss in
the original weight of wool which in the technical term is referred to as ' shrinkage '.
The ' shrinkage ' depends upon various factors like the breed of sheep, the area
in which they graze, the nature of feed, the quality of wool and weather conditions,
etc. It has been estimated that shrinkage of wool may range widely from 78 per
cent to 32 per cent and this is usually referred to in percentage of the original weight
of the grease wool.
In the absence of a suitable method for the determination of shrinkage in wool,
it has been the general practice to estimate the probable shrinkage by visual appraisal.
Though the estimation may come close to the actual shrinkage, in majority of the
cases it is over-or under-estimated consequently proving disadvantageous to the
parties concerned in the trade.
The need for an objective, accurate and expeditious method of making this
determination had long been felt. Several procedures for the laboratory testing
of samples of wool were already available but the major difficulty for which there
was no adequate solution was how to get a sample from a large number of bales of
wool that would correctly represent the entire lot. The problem is claimed to have
been solved by what is known as the ' Core testing ' method developed in the U. S. A.,
which though has not been taken up by any other wool producing country, is now
recognised, in the country of its origin, as an official method for the estimation
of shrinkage in wool. Researches regarding further perfection of the method are
still in progress in the U. S. A. but the method is worth giving trial in India
which may help to improve the present ill-organised wool markets and
increase the confidence of foreign buyers in Indian wools in the international
wool trade. The present paper is an effort to give a short review and description
of the method as practised in the U. S. A. which may be of interest to the wool
trade.
259
104 AR/54
16
260
CORE
TESTING
METHOD
[ Vol. XXIV, Part IV,
EVOLUTION OF THE CORE TEST METHOD
Prior to the advent of the core test method for shrinkage determination in
wool, several methods on bulk consignments were tried but there was no satis-
factory method which could be a reliable check on the accuracy of visual shrinkage.
Dantzer [1922] made a series of tests comparing the shrinkage of small samples
against entire lots, and he found that four 500 gm. samples drawn from a lot of
wool weighing 48,044 lb. gave a shrinkage of 43.4 per cent as compared to 51.4
per cent for the entire lot, a difference of eight per cent.
Jones and Lush [1927] found that the reliability of shrinkage in a sample of wool
depends upon the size of the sample and the variation in shrinkage between
different fleeces in the same flock. Working with fine wool, using 25 fleeces
they found that the shrinkage averaged within two per cent of the true value.
Spencer, Hardy and Brandon [1928] made a study of the shrinkage of wool
taken from the side area of fleeces as compared with the entire fleeces. The shrink-
age of the side samples was 56.8 per cent while that of the entire fleeces was 56.95
per cent.
Wilson [1929] compared the accuracy of 3-pound triplicate hand samples of
wool and found that they varied about three per cent from each other.
Burns [1930] found that duplicate hand samples of wool taken from different
groups of 50 fleeces gave a yield variation of less than two per cent.
Wilson [1931] cited by Robert Burns (loc. cit.) reported a test of three 6- to 7-
pound samples made up by separating handfuls of wool at random in triplicate
from each of the 47 fleeces before they were tied. Three subsamples of about 200
grams were taken from each of the larger samples and scoured separately. The
subsamples agreed in shrinkage but the larger sample varied by three per cent.
Buck and Wood [1936] made a comparison of the shrinkage of side samples
of fleeces against entire fleeces and found that the average shrinkage of the entire
fleeces was 61.86 per cent as compared with 61.55 per cent for the side samples.
Davis, Jones and Warwick [1938 and 1939] were able to work out that small
shoulder samples of wool taken from the fleece at shearing time showed an average
shrinkage difference of 4.94 per cent compared with the shrinkage of the entire
fleeces.
Burns [1940] noted that a series of small hand samples of wool obtained from
sublots of fleeces gave yields within 2.2 per cent of the yields of the entire lots. The
sizes of the three lots tested were 82, 126 and 258 bags.
It was thus evident that hand sampling methods for various reasons proved
inaccurate and slow.
To evolve a satisfactory method of scientific sampling and testing consign-
ments of wool, the Bureau of Customs of the United States of America conducted
an intensive research programme from 1937 to 1941. The efforts resulted in the
development of the ' coring ' method now widely used in the U. S. A. for the
estimation of shrinkage of wool in bulk consignments.
December, 1954 ] G. S. MAHAL AND S. JAYARAMAN 261
Wollner and Tanner [1941] were the first scientists to apply the principle of
core-sampling to grease wool. They found that by drawing 100 cores from a lot
of imported baled wool, the composite sample yield should be within one per cent
of the lot yield.
Johnston, Buck and LeCompte [1944] in preliminary investigations of core
sampling applied to United States domestic wools found that in 58 per cent of the
tests made, the yield of the sample was within one per cent of the lot yield.
Nordskog, Clark and Van Horn [1945] found that 115 cores were necessary to
ensure the yield of the sample being within one per cent of the lot yield.
Clark, Hughes and Buck [1946] cored baled United States domestic wools and
found that 30 cores gave an accuracy within 1.5 per cent between the sample yield
and the lot yield.
Cronin [1947] conducted some tests regarding the size of the coring tube and
used 1- and 2-inch diameter coring tubes in his trials.
Johnston and Davis [1949] reported numerous experiments in coring and pro-
mulgated the improved sytem of core sampling for yield determination which en-
sured practical reliability.
It was concluded that the core sampling method for grease wool shrinkage deter-
mination could be applied in the field and was found practical, reliable and econo-
mical. The procedure consists in the use of an electrically driven tube of standard
pattern which takes a sample representing proportionately the physical characteris-
tics of wool from different bags. The extracted samples taken with the tube from
different bags form a composite sample which is tested in the laboratory for shrink-
age determination. The result thus obtained is considered representative of the
entire consignment from which the sample was drawn. The method is considered
to be far from the error resulting from visual appraisal. The coring method, to
the extent of practical reliability, was perfected in 1945 whereby the shrinkage of
United States domestic wools can be ascertained within one per cent of the true
shrinkages in a great majority of the proof lots tested. Work with regard to the
applicability of this method is still in progress.
It has also been found practicable that core sampling of sacked grease wool in
clips or graded lots can be carried out in the field wherever the representative bags
can be assembled and electric current supply for the drilling machine is available.
As a routine measure, in the U. S. A., the core sampling is conducted at various stages
as given below :
(a) Shearing shed : The wool grower sets aside the representative bags to be
cored while shearing is in progress and coring is done after all the wool in the lot
has been sacked.
(b) Wool warehouse : Representative bags from a clip are set aside as the clip
is being assembled in a warehouse and are then cored.
(c) Loading railway wagons from truck or warehouse : Core samples can be
drawn from the representative bags as the clip is being loaded into the railway
wagons. This method is the most economical because it involves a minimum of
extra labour.
262
CORE
TESTING
METHOD
[Vol. XXIV, Part IV,
EQUIPMENT NEEDED FOR SAMPLING
The following tools are necessary to carry out the sampling from a
consignment :
1. Drill
2. Extraction cylinder
3. Blade retaining ring
4. Cutting blade
5. Cables, plugs, reamer, honing stone, bale cutting knife and spares.
Drill : The drill is a three-quarter inch portable electric drill with a pipe
handle and a pistol grip. It has a cone-shaped spindle meant to accommodate
an extraction cylinder adapter with tapered hole pressure forced on to spindle.
Extraction cylinder : This consists of three separate segments welded
together, the barrel, cutting end flange and the drill end flange. Originally two
types of tubes were used, one 18 inches long and two inches in diameter and the
other 30 inches long and two inches in diameter. According to Johnston and Davis
[1949] the two inch diameter tubes, both the 30 inch and 18 inch long cylinders,
were not found to cut and retain uniform cores because their diameter was not big
enough to allow the passage of heavy shrinking greasy lumps of wool and large
tags. They also observed that in areas of low density wool, the tube with two inches
diameter did not cut and retain the wool but pushed it aside. It was also found
that ' roping ' of the cores within the tubes caused them to become constricted
and thus to pull out of the tube and remain within the bag when the tube was with
drawn. The authors also reported that the difficulty could be overcome by com
pressing the wool in the bag by a simple wooden beam press but it consumed con
siderable time. The following dimensions and features have been suggested by the
authors to obviate the above-mentioned difficulties.
(1) 2⅞ inches in diameter at the blade.
(2) A peaked, projecting, spiral ridge 1/8 inch deep running once around the
throat of the tube. This was to prevent the core being pulled out of
the tube.
(3) Inside diameter of the tube, three inches. This allowed the wool in the
core a certain amount of expansion after passing through the
2¾ inch diameter throat.
(4) A length of 24 inches.
Reamer : This is a simple rod used to push sample of wool from the extraction
cylinder.
Cutting blades : This is a ring-like flexible cutting piece with one edge sharp
and the other blunt. Many types of blades are reported to have been tried with
varying success. Lyons [1950] reports that an effective blade is cycloid (pointed
peak, round valley), two inches long, ½ inch wide and points ½ inch apart. The
average life of the blade depends upon the type of wool being cored. Wool with
high content of solid impurities, such as stones or metal objects, reduces the life
of the blade. According to Lyons (loc. cit.) a blade may normally be used for as
Indian J. vet. Sci., Vol. XXIV, Part IV. ]
PLATE
XIV
Fig. 1. Coring equipment
1. The drill. 2. Extraction Cylinder. 3. Blade retaining ring. 4. Cutting blade. 5. Reamer.
Fig. 2. Sampling for core testing
Photo courtesy, United States Testing Co., Inc. Hobken, N. J. (U.S.A.)
PLATE XV
[ Indian J. vet. Sci., Vol. XXIV, Part IV
Fig. 3. A wool analytical laboratory
Photo courtesy, United States Testing Co., Inc. Hobokin, N. J. (U.S.A.)
Fig. 4. Coring locations in a bag for obtaining representative sample.