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REPORT OF THE KING INSTITUTE, GUINDY
PART II.—SCIENTIFIC AND GENERAL.
(A) VACCINE LYMPH.
1. Charge of work .—The Assistant Director Dr. C. G. Pandit was in charge
of the section throughout the year and has collaborated in writing this portion of
the report.
2. Seed lymph .—Nijland's method continues to give satisfactory results and
little difficulty was experienced in maintaining the potency of seed lymph. The
desirability of continuing the passages of seed lymph during the hot weather was
investigated and some interesting results have been obtained. The first effect of
the adverse·conditions associated with passage in the hot weather was deteriora--
tion of practically all the strains of lymph used, but it was noted that these strains
regained their virulence much earlier as judged by the yield of pulp and the
potency of the cups manufactured, than strains which were cold stored and not
passaged during the hot off-season as has been the practice hitherto. Evidently
the "freshness" if it be so called of the seed lymph at the commencement of
manufacture counts for a great deal.
But further experience is needed before a definite opinion can be arrived at
and hot weather passages are adopted as a routine. Experiments are being under-
taken to see if vaccinifers other than rabbits or buffaloes, e.g., donkeys, can be
substituted anywhere in the Nijland cycle with better results.
3. The potency of lymph manufactured.— This is judged by
(a) Potency on calves as judged by the vesiculation test.
(b) The case and insertion success rates obtained in primary vaccination
on children.
(c) Its immunising value against smallpox which is really the most
important criterion.
These three points may now be discussed : —
(a ) Potency as judged by the vesiculation test.— This test was introduced in
1922 by Cunningham and Cruickshank as a standard of potency of vaccine lymph.
Lymph is diluted 500 times and a known quantity of diluted lymph is introduced
into linear incisions the total length of which is noted. The developed vesicles
are counted and the result expressed as so many vesicles per inch. It was pointed
out at the time that lymph which yielded only one vesicle per inch was sufficiently
potent to ensure a case success of 90 per cent when used in the Presidency. As
lymph improves in potency, more and more vesicles develop along the linear
incisions until finally they cannot be counted then the cup of lymph is called
"continuous." Some cups where such a count was possible were designated as
"discrete." The proportion of "continuous" cups to the "discrete" ones out
of total number of cups manufactured from 1922 onwards is as follows :—
Year.
Total number
of cups
manufactured.
Percentage of almost
continuous and
continuous.
Per cent.
1922-23
125
8.0
1923-24
124
55.6
1924-25
175
73.7
1925-26
175
90.9
1926-27
174
98.8
These figures show in a striking manner the value of Nijland's method
introduced in 1922 in greatly maintaining the potency of the seed lymph. The
maximum level was reached this year.
( b) Vaccination rates.—Prior to issue elsewhere, all the cups manufactured
were issued to vaccinators in the Saidapet Range and case and insertion success
rates of 100 per cent. and 99 per cent. respectively were obtained. These are
what may be called cup test rates. Hitherto they have not been separately
reported, but instead the rates for the general primary vaccination results in the