16
REPORT OF THE KING INSTITUTE, GUINDY.
TABLE II.
Average yield of lymph per calf according to years.
Year.
Grammes.
1904
...
...
...
...
... ...
1905
...
...
...
...
... ...
1906
...
...
...
...
...
...
l907
...
...
...
...
...
...
1908
...
...
...
...
... ...
1909
...
...
...
...
... ...
1910
...
...
...
...
... ...
1911
...
...
...
...
...
...
1912
...
...
...
...
... ...
1913
...
...
...
...
... ...
4.9 The records are incomplete, this
figure would be lower.
3.5
No records.
3.2
2.8
3.7
5.1
5.3
5.9
5.3
This table is of interest for it clearly shows that more lymph has been obtained per calf
during the last four years than during the earlier ones. The reason for this is twofold. In
the first place the improved technique of inserting the seed lymph in groups of triple lines
results in the formation of larger and healthier vesicles ; there is a greater flow of blood to
the parts and a better re-action, and the vesicles run together to form a uniform layer of
lymph. In the case of the single lines in the majority of the animals the vesicles remain small,
and there is a marked tendency for them to mature and dry up between 72 and 86 hours.
The second reason for the better results is due to the routine practice which I introduced in
1911, and which has since been continued, of vaccinating a larger number of calves simulta-
neously, ten in the morning and ten in the afternoon. The vesicles mature about the same
time, and the observer has a wide margin from which to select the seed for the next batch
of calves. In a very short time the eye becomes accustomed to the type of vesicle which
gives the best results. The strain is rapidly passed through a large number of calves which
are, as far as possible, never kept for long periods at the Institute (only on an average five to
six days) ; the seed lymph except during intervals when vaccination is stopped is never kept
for long periods. Calves kept for any length of time at the Institute soon begin to deteriorate ;
there is practically no fresh grazing to be had ; they become infested with the calf louse,
Haematopinus vituli, Enderlein, and latterly have developed a fungus disease of the skin
simulating acariasis. Calves so infested with lice and the skin disease are unsuitable for
purposes of vaccination.
Latterly the technique of using the seed lymph has been further improved. If it is not
to be used immediately it is without any further treatment placed in a sterile petri dish and
stored in the cold room. When required it is pulped and mixed either with glycerine or with
sterile saline solution, and then used for vaccinating the calves. Fivehundred and eighty-one
calves were vaccinated in this way during the months of February and March 1914 and 5,413.4
grammes were collected from them, each calf yielding on an average 9.31 grammes. All the
vesicles were well formed and typical; the lymph produced normal vesicles on children
vaccinated at Saidapet.
After a long series of passages through the calf the organism (?) of vaccinia becomes
attenuated. This has long been recognised, and a recent observer has again drawn attention
to the fact that the donkey is the best animal for exalting the virus ; unfortunately this
animal is most difficult to procure locally. Failing this it has been found best to introduce
the seed from different parts of the country and select the one which gives the best results.
The rapid passage through a large number of healthy calves at definite periods of the year,
especially avoiding the hot months of April, May and June, storing several good masses of
vesicles in the semi-dry state for very short periods, pulping and mixing these either with
glycerine or sterile saline solution is the routine technique now employed.
It is interesting to note that about 6 per cent. of the calves are rejected as failures, i.e.,
either no vesicles have formed at the site of vaccination or only a few abortive ones. I believe
that at least some of these animals have already had vaccinia and are either wholly or partially
protected. The success rate in calves works out at 94 per cent. If a proportion of calves (6 per
cent.), which are vaccinated with seed of a known potency and which give excellent results on
several other animals vaccinated at the same time and over a comparatively enormous area
of skin, fail to take, how much more is it likely that a proportion of children vaccinated over
a comparatively small area of skin and often under most unfavourable circumstances will fail
to take, or take badly. If the success rate in calves is 94 per cent. one can hardly expect it
to be higher in children unless they are vaccinated with the greatest care and all precautions
are taken to see that the vaccinated areas are not interfered with ; this is in many cases
impossible in the case of village children.
A perusal of the figures I have quoted lends no support to the view I have heard
expressed that better cow-pox vaccine was obtained in the earlier years of the work of the
vaccine section than during the later years. I have no hesitation in saying that the vesicles¬
produced as the result of triple lines are better than those from single lines.