K. S. NAIR, D. NILAKANTA AYYAR AND A. R. MADHUSUDAN 387

Calves Nos. 155 and 156 have, however, shown a slight thermal rise after
the retest dose and this can only be regarded as due to causes other than Rinder-
pest reactions. Perhaps it was due to Theileriasis since Theileria mutans
was present in the blood of these animals.

Ordinarily, a dose of more than 30 c.c. of serum per 100 lb. body-weight
is not employed in serum simultaneous inoculations in which case a blocked-
out reaction is not produced, and when a blocked-out reaction does occur as a
result of employment of higher doses, it does not interfere with the establish-
ment of immunity. The conception that a blocked-out reaction will not
confer a high degree of immunity is not in conformity with the results obtained
in this study.

                              CONCLUSIONS

1.  Under the conditions of this experiment the immunizing value of a
' blocked-out' reaction was not inferior to those in which symptom synd-
rome was present.

2.  This phenomenon can be brought about among susceptible buffalo -
calves in serum simultaneous inoculations by giving a uniform dose of 1 c.c.
of Rinderpest virus to each individual and 40 c.c. or more of anti-
Rinderpest serum to every 100 lb. body-weight of the animal.

                                   SUMMARY

Experiments were undertaken to find out if a ' blocked-out ' reaction
brought about by massive doses of serum in animals inoculated by serum
simultaneous method, would interfere with the production of immunity.
Young susceptible buffalo-calves were inoculated by the serum simultaneous
method employing an infective dose of 1 c.c. of virus and serum at doses of
25 c.c. 30 c.c., 35 c.c., 40 c.c., 45 c.c., and 50 c.c., per 100 lb. body-weight.
From a study of the reactions in these calves, it was observed that calves that
received serum up to 35 c.c. per 100 lb. body-weight reacted to the inocu-
lation and those that received higher doses did not show any reaction but
without interfering with the production of immunity as judged by the
absence of reactions in these calves to a subsequent test dose of virus. So,
it is concluded that 'blocked-out' reactions do not in any way hamper the
production of immunity.

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