NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
2
Freezing Point Test for Buffalo's and Cow's Milk
EXPERIMENTAL
Apparatus and method used for the determination of the freezing point of
milk.—A Beckmann freezing point apparatus as described by Andrew [1929]
was employed. This is a simple instrument capable of giving accurate and
reproducible results. In this apparatus the tube containing milk is separated
from the cooling mixture of ice and salt by an air space. Two thermometers
are used, the control and the regular. The latter, of Beckmann type, is gradu-
ated to hundredth of a degree centrigrade and it can be read to half a gradua-
tion. It is checked repeatedly at regular intervals by determining the freez-
ing point of fresh glass distilled water and chemically pure sucrose solution.
For the determination of the freezing point, the sample under test was
supercooled to —2°C. in a separate vessel and the tube containing the milk
was then wiped dry and transferred to the main apparatus. Stirring was
continued at an even rate. The mercury column after falling steadily suddenly
jumped up and remained constant for some time at a figure which was taken
as the freezing point.
This method was applied to a large number of samples of genuine milk
and then tested under various conditions of adulteration likely to occur in
practice as described below.
(i) Freezing point of cow's and buffalo's milk.—One hundred and fifty
samples of buffalo's milk and fifty of cow's milk were examined. The buffalo's
milk was obtained from animals of Murrah breed, that of cow's from Sindhi,
Gir and cross-bred animals. A few samples of buffalo's milk obtained from
animals kept under average village conditions were also included. All the
determinations on them were made within two or three hours of the milk being
drawn and for this the samples were kept in a cool and clean place to ensure
their remaining perfectly sweet. It was previously observed that at the pre-
vailing temperature (about 80°F.) no rise in acidity occurred until about six
hours after milking. The determinations were made on morning milk in the
case of buffaloes and on evening milk in the case of cows. A summary of
these results is given in Table I showing clearly the variations observed.
TABLE I
Freezing point of buffalo's and cow's milk
Kind of milk
Buffalo milk
Cow milk
No.
of
sam-
ples
150
50
Distribution of figures
—0.525°C.
No.
3
...
Per
cent-
age
2
...
—0.530°C.
No.
24
1
Per
cent-
age
16
2
—0.535°C.
No.
15
2
Per
cent-
age
10
4
—0.540°C.
No.
35
12
Per
cent-
age
23.3
24
—0.545°C.
No.
25
17
Per
cent-
age
16.7
34
—0.550°C.
No.
24
10
Per
cent.
age
16
20
—0.555°C
No.
10
5
Per
cent-
age
6.66
10
—0.560°C.
No.
10
3
Per
cent-
age
6.66
6
—0.570°C.
No.
4
...
Per
cent-
age
2.66
...
ZAL R. KOTHAVALLA, J. S. BHALLA & N. D. LAVANGIA 3
The normal range obtained for buffalo's milk was —0.530°C. to —0.560°C.
Over 95 per cent of the figures fell within this range, the extremes being
—0.525°C. and —0.570°C. In the case of cow's milk over 88 per cent of the
figures were within the range of—0.540°C. to —0.550°C., the extremes being
—0.530°C. and —0.560°C. Thus it will be seen that the average figures for
the freezing point of genuine cow and buffalo milk fall within a narrow range
of —0.543°C. to —0.546°C. These results are in close agreement with those
reported in the previous work of Leather [1914], Elsdon and Stubbs [1931],
and others.
(ii) The freezing point of milk in relation to its acidity.—A serious drawback
with the freezing point test is its failure to give constant figures with milk that
is not perfectly sweet.
The production of lactic acid on standing,
which is in itself an ionizable substance, results in more mineral matter
passing into solution, causing an increase in osmotic pressure. This in its
turn brings down the freezing point. The acidities of fresh samples of
milk whose freezing points have been determined [Table I] are given in
Table II.
TABLE II
Acidity (lactic acid per cent) of samples examined for freezing point in Table I
Kind of milk
Buffalo milk . . .
Cow milk . . .
Total
number
of
samples
examined
135
50
Distribution of figures
0.09
No.
1
...
Per-
cent-
age
0.74
...
0.10
—0.125
No.
18
8
Per-
cent-
age
13.33
16
0.130
—0.155
No.
70
10
Per-
cent-
age
51.85
32
0.160
—0.188
No.
40
22
Per-
cent-
age
29.63
44
0.190
—0.210
No.
5
4
Per-
cent-
age
3.70
8
0.230
No.
1
...
Per-
cent-
age
0.74
...
The normal range obtained for buffalo's milk was 0.10 to 0.18 per cent
lactic acid. Over 94 per cent of the figures fell within this range, the extremes
being 0.09 and 0.23 per cent. The average of 135 determinations was 0.148
per cent. In the case of cow's milk the range was from 0.10 to 0.19 per cent
lactic acid, the extremes being 0.10 and 0.20 per cent. The average of fifty
determinations was 0.154 per cent.
In Table III figures are given for the freezing point of fresh milk, mostly
from buffalo, and showing quite high acidity.
4
Freezing Point Test for Buffalo's and Cow's Milk
TABLE III
Freezing point of normal milk showing high acid content.
Acidity
0.18
0.18
0.19
0.20
0.21
0.23
Freezing point (—0°C.)
0.530 ; 0.535 ; 0.535 ; 0.535 ; 0.545 ; 0.550 ; 0.555 ; 0.555 ; 0.560 ;
0.540 ; 0.555 ; 0.560 ; 0.560 ;
0.530 ; 0.540 ; 0.545 ; 0.545 ; 0.550 ;
0.530 ; 0.550 ;
0.525 ; 0.530 ; 0.550 ;
0.535
The data in Table III show that no correlation exists between the freez-
ing point value and the acidity and that even fresh high acid milk samples
give values for freezing point which are fairly within the normal range cited
before.
The degree of acidity of a milk sample at which the freezing point deter-
mination can be made without fear of any error creeping in due to this factor,
differs according to various authors. Keister [1917] has observed an increase
of 0.03°C. in the depression in freezing point for every 0.01 per cent rise over
0.15 per cent lactic acid. Parker & Spackman [1929] suggest the addition
of 0.01°C. to the observed freezing point for every 0.01 per cent increased
acidity if the increased acidity is between 0.14 and 0.17 per cent, and of
0.003°C. if the range is from 0.17 to 0.6 per cent. The Association of Official
Agricultural Chemists [1940] recommends 0.18 per cent lactic acid as
the maximum titratable acidity allowed for samples meant for freezing
point determination. The results obtained in this experiment showed that
the natural acidity of milk did not appreciably interfere with the test and any
variation was well within the limits of experimental error.
(iii) The freezing point of milk as influenced by its adulteration with distilled
water.—A number of determinations was made on samples of buffalo's milk
adulterated with five, ten, twenty and fifty per cent of distilled water in
order to find out to what extent the results agreed with the figures of adultera-
tion percentage calculated by various methods from the freezing point values
obtained for adulterated samples. In each case the percentage of adulteration
was calculated both from the tables given by Winter [1914] and Leather [1914]
and from the formula of Hortvet [1921]. In the latter case the percentage
adulteration was calculated by taking the actual values for watered and
unwatered milk obtained from the determinations on samples of buffalo's
milk and also by assuming the value for unwatered milk as —0.53°C. and work-
ing out the percentage from the value obtained for adulterated samples. It
will be seen from Table IV that, when the actual figures for both un-
watered and watered samples are used, the percentage adulteration calculated
is in excess of the true figures by about one per cent. When the freezing point
of normal milk, however, is taken as —0.53°C. it is less than the true figure
by the same amount.
ZAL R. KOTHAVALLA, J. S. BHALLA & N. D. LAVANGIA 5
TABLE IV
The difference between the true percentage of water added and the percentage adulteration calculated
by various methods
Average, minimum and maximum difference between the true percentage of water added and the percentage calculated
True
percentage
of
water added
5
10
20
50
Number
of
determina-
tion
25
25
25
10
Average
By use of formula (A)* using
actual values obtained for both
unwatered and watered samples
Min.
—0.28
+ 0.09
+ 0.37
+ 0.91
Max.
+ 0.66
+1.11
+1.82
+1.85
Average
+ 0.21
+ 0.532
+ 1.02
+ 1.48
+ 0.81
By the use of formula (A)*
taking the F. P. value of un¬
watered sample at —0.53°C. in
all cases
Min.
—0.28
+ 0.37
—0.19
0
Max.
—4.057
—3.34
—2.07
+ 0.944
Average
—1.83
—1.35
—0.68
+ .038
—0.87
According to Winter's figures
from the F. P. value actually
obtained for watered samples
Min.
+0.40
—0.10
—0.7
+0.40
Max.
+ 4.00
+ 3.50
+ 3.4
+ 2.20
Average
+ 1.62
1.85
2.03
1.66
+ 1.79
According to Leather's tables,
using F. P. values actually
obtained for watered samples
Min.
—0.3
—0.08
0.358
—0.932
Max.
+2.31
—1.82
—1.38
—2.67
Average
+ 0.013
+ 0.054
—0.940
—1.454
—0.58
*Formula (A) according to Hortvet [ 1921]
Percentage of water added
.
.
.
.
.
.
.
.
.
.
.
=100 (T—T) / T
Where T= F. P. of unwatered sample and T = F. P. of watered sample
ZAL R. KOTHAVALLA, J. S. BHALLA & N. D. LAVANGIA 7
TABLE V
Freezing point of milk as affected by pasteurization and boiling
Sample
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
F. P. of raw
milk —°C.
0.530
0.530
0.545
0.555
0.550
0.545
0.540
0.540
0.550
0.540
0.550
0.550
0.550
0.540
0.550
0.550
0.540
0.550
0.550
0.540
0.550
0.550
0.540
0.540
0.540
F. P. of
pasteurized
milk — °C.
0.535
0.535
0.545
0.560
0.555
0.545
0.545
0.545
0.555
0.550
0.555
0.555
0.555
0.540
0.555
0.555
0.545
0.550
0.555
0.540
0.555
0.555
0.545
0.540
0.540
F. P. of boiled
milk —°C.
0.555
0.555
0.565
0.575
0.580
0.570
0.560
0.560
0.575
0.565
0.570
0.570
0.570
0.560
0.575
0.570
0.570
0.570
0.575
0.560
0.570
0.570
0.565
0.560
0.570
Average
Depression in
F. P. due to
Pasteurization
—°C.
0.005
0.005
0.0
0.005
0.005
0.0
0.005
0.005
0.005
0.01
0.005
0.005
0.005
0.0
0.005
0.005
0.005
0.0
0.005
0.0
0.005
0.005
0.005
0.00
0.00
0.0038
Depression in
F. P. due to
boiling —°C.
0.025
0.025
0.020
0.020
0.030
0.025
0.020
0.020
0.025
0.025
0.020
0.020
0.020
0.020
0.025
0.020
0.030
0.020
0.025
0.020
0.020
0.020
0.025
0.020
0.030
0.0228
ZAL R. KOTHAVALLA, J. S. BHALLA & N. D. LAVANGIA 9
TABLE VI
Freezing point value as affected by presence in milk of saturated solution of mercuric chloride
Amount
of
HgCl 2 per
100 ml. of
milk
2 drops .
4 drops .
½ c.c. .
¾ c.c. .
1 c.c. .
2 c.c. .
3 c.c. .
5 c.c. .
Fresh
milk
Min.
temp.
Max.
temp.
F. P. °C
.535
(.16)
.535
(.16)
.535
(.16)
.535
(.16)
.535
(.16)
.535
(.16)
.535
(.16)
.540
(.11)
1st
day
72
86
.535
(.16)
.535
(.16)
.535
(.17)
.535
(.18)
.540
(.19)
.540
(.23)
.540
(.24)
.545
(.27)
2nd
day
71
89
..
(.44)
.535
(.17)
.535
(.18)
.540
(.19)
.540
(.20)
.540
(.23)
.540
(.24)
.545
(.27)
3rd
day
74
87
.535
(.18)
.585
(.18)
.540
(.19)
.540
(.20)
.540
(.24)
.540
(.25)
.545
(.27)
4th
day
72
84
...
(.36)
.540
(.19)
.540
(.19)
.540
(.20)
.540
(.24)
.540
(.25)
.545
(.27)
5th
day
70
83
.545
(.20)
.545
(.20)
.540
(.20)
.540
(.25)
.540
(.26)
6th
day
68
82
.545
(.20)
.545
(.20)
.540
(.20)
.540
(.25)
.540
(.26)
7th
day
70
80
...
(.31)
.545
(.20)
.540
(.20)
.540
(.25)
.540
(.24)
8th
day
70
82
.545
(.20)
.540
(.20)
.540
(.25)
.540
(.24)
9th
day
69
82
.545
(.20)
.540
(.20)
.540
(.22)
.540
(.22)
10th
day
71
89
.545
(.20)
.545
(.21)
.540
(.22)
.540
(.23)
11th
day
72
82
...
(.35)
.550
(.22)
.540
(.28)
.540
(.24)
12th
day
72
80
...
(.30)
.540
(.24)
.540
(.24)
13th
day
72
78
.540
(.24)
.540
(.25)
14th
day
73
80
.540
(.25)
.540
(.25)
15th
day
74
80
...
(.27)
.540
(.25)
16th
day
73
78
...
(.30)
.540
(.28)
N.B.—Results in brackets are the actual acidities as percentages of lactic acid.
10
Freezing Point Test for Buffalo's and Cow's Milk
TABLE VII
Freezing point value of foremilk and strippings
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Foremilk
F. P. — °C.
0.550
0.545
0.545
0.540
0.530
0.545
0.550
0.545
0.540
0.545
0.545
0.540
0.545
0.545
0.545
Fat per cent
1.9
1.6
1.7
1.6
1.7
1.7
1.9
1.7
1.9
1.7
1.6
1.7
1.6
1.7
1.3
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Strippings
F. P. —°C.
0.550
0.545
0.535
0.545
0.535
0.555
0.550
0.550
0.545
0.545
0.550
0.545
0.545
0.540
0.545
Fat per cent
4.6
9.8
6.5
8.5
8.5
8.0
12.4
10.0
7.6
11.2
9.4
8.2
8.6
10.2
8.2
TABLE VIII
Freezing point value of milk obtained from animals going dry
No.
1
2
3
4
5
6
7
8
Acidity (lactic acid per cent)
0.04
0.06
0.11
0.15
0.04
0.08
0.11
0.11
F. P. —°C.
0.540
0.545
0.545
0.545
0.550
0.565
0.545
0.545
corresponding value was —0.546°C.* These results are in very close agreement
with those reported for cow's milk by workers in other countries. The
average acidity of these samples was 0.15 per cent lactic acid.
It was observed that the high natural or apparent acidity of milk did not
interfere with the freezing point value, which remained within the normal range
in samples showing acidity varying from 0.18 to 0.23 per cent (lactic acid).
*The results published here were obtained in 1938 using the apparatus designed
according to Beckmann. Since then similar investigations have been carried out at the
Agricultural Institute at Allahabad (results unpublished) using an improved type of ap-
paratus as recommended by Hortvet. The general results obtained at the Allahabad
Institute are in close agreement with the conclusions of the present authors.
14
The Blood Groups of Indian Cattle and Buffaloes
Usuelli [1931], in studying the blood groups of Bos taurus, found that group Ao and
Oa occurred almost exclusively in animals descendant from the Podolian breed
while Swiss and Holstein breeds belonged to group Oo, with the exception of a few Swiss
cattle of group Ao. Karshner [1928] found isoagglutinins in the blood of bovines but
states that they are less common than in the blood of man. Reactions are less frequent
among bovine animals of the same strain than among those of widely divergent strains.
Schermer [1932] states that there appears to be a difference of opinion as to whether cattle
have three or four groups.
The problem of differentiating the various breeds of cattle in India and
of deciding whether particular animals ought to constitute ' breeds' or
merely ' local varieties' is one which has exercised many minds. Until
a few years ago there was considerable disagreement on these matters among
persons qualified to express an opinion ; even now it cannot be said that
complete agreement has been reached, while the criteria that are used for classi-
fication are largely physical or morphological. The issues have now been
considerably clarified, thanks to the observation of Olver [1938] and Ware
[1939, 1941], working through the medium of the Imperial Council of Agri-
cultural Research.
No previous work has been carried out in this country on the grouping
of bovine bloods. By doing so now, it was hoped that some light might be
thrown on the origin and relationship of Indian cattle. It was necessary,
however, to determine in the first place whether blood groupings can be
accurately distinguished. The first experiments were, therefore, conducted
on cattle of the Hariana breed, a few Kumauni hill bulls, Dhanni bullocks
and on buffaloes, such as were available on the farm of this Institute. A
few samples of sera and corpuscles were also available from other cattle
breeds. Finally, a considerable number of Hariana cattle at the Govern-
ment Cattle Farm at Hissar were tested.
METHODS
In view of the findings of Hopp [1920], according to which the blood-
groups in children are only established after one year of age, adult animals
only were used in these experiments. The technique for studying isoagglu-
tinins in human practice has been fully worked out but in veterinary science
much further work remains to be accomplished. At first, the slide and plate
methods, originally adopted by Moss, Lee and Vincent, quoted by Lauer
[1930], were used but those proved to be entirely unsatisfactory with cattle.
We have, therefore, used the tube method, in which a certain quantity (say
four drops) of serum is poured into small test tubes (size 7 cm. × 1 cm.) and
an equal quantity of 2 per cent corpuscle suspension added. The mixture
is then gently shaken and placed in a dry incubator at 37°C.
Serum was taken from the clot, and corpuscles by drawing blood into
small bottles containing 2.5 per cent. sodium citrate in saline—one volume
citrate solution and 10 volumes of blood. The cells were then well washed
with saline on the centrifuge.
BALWANT
SINGH
15
When the reaction is positive, the cells form clumps which may float
in the liquid, may settle as granular masses or may adhere to the bottom
from which they can only be separated by rigorous shaking. Cases where
there is granulation but with disappearance of the clumps on shaking were
recorded as negative.
Stability of red cells and of isoagglutinating serum.—Before proceeding
to large-scale experiments, it was essential to investigate a number of technical
points such as the stability of cells and sera, when stored in the refrigerator
at 9°C. The experiments, full details of which are given in Table I, were
carried out regarding the stability of the red cells.
TABLE I
Stability of red cell suspension
Cells stored for days
0 . . .
7 . . .
8 . . .
14 . . .
18 . . .
21 . . .
22 . . .
28 . . .
Fresh serum of cow 94
Cells from
Buffalo
95
+
+
+
+
+
Ox
15
+
+
+
+
+
Ox
14
+
+
+
+
+
Ox
16
+
+
+
+
+
Cow
64
+
+
±
+
—
Cow
123
+
+
±
±
—
Cow
33
+
+
+
±
+
Fresh serum
of
hill bull 214
Cells
from
Ox
15
+
+
+
+
+
Ox
16
+
+
+
+
+
COW
48
+
+
+
+
+
Fresh
serum of
cow 131
Cells from
Buffalo
59
+
+
+
+
—
+ Complete reaction.
± Incomplete reaction.
— Negative.
From Table I, it will be seen that in most cases the cells remain agglutd
nable for at least 28 days. Cells from two animals (cows 64 and 123) failei¬
to agglutinate on the 28th day, although they were agglutinable on the 21st
day. It was thus sufficiently established that washed cells, kept in the ice
chest, could safely be used for a period of 21 days.
Table II shows the results of tests as to the stability of isoagglutinins
after removal from the body and stored at 9°C.
16
The Blood Groups of Indian Cattle and Buffaloes
TABLE II
Stability of Isoagglutinins
Corpuscles from
Buffalo 59 . . .
Buffalo 16 . . .
Dhanni Bullock 15 .
Buffalo 59 . . .
Buffalo 16 . .
Dhanni Bullock 15 .
Serum
from
Cow 131 .
Cow 123 .
Hill bull 222
Cow 94 .
Hill bull 214
Period
(hours)
of
storage
0
24
48
72
0
24
48
120
0
24
48
120
0
24
48
72
0
24
48
72
Serum dilutions
1 : 2
+
+
+
—
+
+
+
—
+
+
+
—
+
+
+
—
+
±
—
—
1 : 4
+
+
+
—
—
—
—
—
+
+
+
—
—
—
—
—
—
—
—
1 : 8
—
—
—
—
—
—
—
—
±
±
—
—
—
—
—
—
—
—
—
—
1 : 16
—
—
—
—
—
—
—
—
±
—
—
—
—
—
—
—
—
—
—
—
Time
(minutes)
taken
for
agglutina-
tion
20
20
30
...
40
40
...
...
20
20
...
...
20
20
30
...
30
60
...
...
BALWANT
SINGH
17
From these results, it is noted that sera from cows 131, 123, 94 and hill
bull 222 remained active in dilutions of 1 : 2 for 48 hours, while the serum
from hill bull 214 began to deteriorate after 24 hours only. Isoagglutination
was complete after 20-40 minutes.
A number of strongly reacting sera and cells were examined for the
presence of a prozone phenomenon but this was not observed, while at the
same time it appeared that positive reactions were to be expected with serum
dilutions of 1 : 2 or 1 : 4 but not higher.
Reactivation of heated or stored ox serum.—In human practice, where
sera from all four groups remain active for a considerably longer time, the
determination of groups does not present much difficulty. In the case of
animals, however, the stability of isoagglutinins outside the body is very
low. This unfortunately prevents the transit of sera over long distances and
restricts observations to a limited number of animals. Little [1929] en-
countered similar difficulties and found that the addition of fresh cow serum
to isoagglutinating serum, which had deteriorated as a result of heating or
storage, was capable of restoring the isoagglutinating property. Although
the point is not made very clear in Little's articles, it appeared possible that
the loss of isoagglutinating power was simply due to disintegration of com-
plement. A few experiments were, therefore, carried out on the reactivation
of sera by means of fresh cow and guinea-pig serum (Tables III and IV).
TABLE III
Reactivation of isoagglutinating serum, rendered inactive by heat at 60°C.
Isoagglutinating serum from
Cow 131 . . . . .
Cow 94 . . . . .
Bullock 7 . . . . .
Hill bull 214
.
.
.
.
.
Fresh serum from cow 34, etc. added in percentages shown
Cow 34
10 25 50
— — —
+ + +
(± + ±)
— — —
— — —
Cow 37
10 25 50
— — —
± — —
(— — — )
— — —
— — —
Hariana
cow 59
10 25 50
— — —
— — —
— — —
— — —
Guinea pigs
1, 3 and 4
10 25 50
— — —
— — —
— — —
— — —
Guinea
pig 2
10 25 50
— — —
+ + +
— — —
— — —
NOTES
(1) Fresh red cell suspension from the same animal was used throughout.
(2) Isoagglutinating sera before heating were positive and after heating were negative.
(3) The tests were repeated once with the bovine sera and results which differed are shown in brackets.
It is seen that serum from cow 34 and from guinea-pig 2 reactivated the
serum of cow 94. The fresh sera from two other bovines and from three other
guinea-pigs were inactive.
18
The Blood Groups of Indian Cattle and Buffaloes
TABLE IV
Reactivation of serum, isoagglutinins of which had disappeared on storage
Isoagglutinating
scrum from
Cow 131 . . .
Cow 94 . . . .
Bullock 7
.
.
.
Hill bull 214 . . .
Percentage of fresh serum added
Cow 34
10 25 50
— — —
± + ±
( + )
— — —
*
± ± ±
*
(+ + +)
Cow 37
10 25 50
— — —
— — —
— — —
— — —
Cow 59
10 25 50
— — —
— — —
— — —
— — —
Guinea-pig 5
10 25 50
— — —
— — —
— — —
— — —
Guinea-pig 6
10 25 50
— — —
+ ± ±
— — —
— — —
Guinea-pigs
7 and 8
10 25 50
— — —
+ — —
— — —
— — —
* Issoagglutination took place at room temperature after the tubes were removed from the incubator.
NOTES
(1) Fresh red cell suspension from the same animal was used throughout.
(2) Isoagglutinating sera before storage were positive and after storage were negative.
(3) The tests were repeated once with the bovine sera and results which differed are shown in brackets.
In the experiments with stored sera, the serum of cow 34 reactivated
the sera of cow 94 and hill bull 214, although positive reactions with the
latter were only seen after the tubes had been allowed to remain for a time
at room temperature. Guinea-pig 5 serum was negative, while that of guinea-
pig 6 gave a positive reaction with the serum of cow 94. Serum from guinea-
pigs 7 and 8 were positive for cow 94 serum, when serum was present at 10
per cent strength. Optimal amounts of serum appear to be about 25 per
cent in the case of cattle sera and 10 per cent with guinea-pig sera.
In order to ascertain if complement, which may be present in normal
ox serum, is the active agent in the reactivation of cattle sera which have
lost their isoagglutinating power, experiments were undertaken to measure
the complementary activity of ox serum, using for the purpose an anti-ox cell
amboceptor prepared in rabbits. The amboceptor serum so prepared was
highly active but these experiments gave negative results, four samples of
ox serum tested at random appearing to be entirely devoid of complement.
Since complement is certainly present in fresh guinea-pig serum, it follows
that the reactivating agent present in fresh serum can scarcely be identical
with complement.
EXPERIMENTAL RESULTS
Investigations on the existence of blood-groups among the cattle and
buffaloes of this Institute were commenced in December, 1940. Seventeen
experiments, using 159 cattle and 48 buffaloes, were conducted. In all,
2 883 combinations between sera and red cells were set up. These animals
belonged to the Hariana, Kumauni ' hill' and Dhanni breeds of cattle and
' plains ' buffaloes and were of widely divergent strains. The principle that
' the more foreign the stimulus, the stronger ought to be reaction [Szyma¬
nowski, 1934]' would be expected to apply in this case.