IMMUNITY IN CALVES INOCULATED BY GOAT VIRUS AGAINST RINDERPEST     343

Balwant Singh (loc. cit.) the factor of greatest importance appears to be the age of
the animals at the time of the inoculation as shown in Table II below.

                                                                                                        TABLE II.

                                                     Distribution of calves reacting to test dose, according to age at immunisation and
                                                                                                     interval of test.

It will be seen from the above table that only two of the nine calves immu-
nised after the attainment of 3 months can be stated to have reacted to the test
inoculation and in the case of these two animals the reaction was very slight and in
one case of doubtful origin. In the case of the animals immunised below the age
of 3 months all reacted in greater or less degree—a result not unexpected in view
of the earlier observations on the use of bull virus in very young calves. None of
the reactions observed in this series were, however, of a grave nature and it is to
be presumed that although immunity had been conferred by the first inoculation,
such immunity was of low degree and was waning comparatively rapidly.

Although the results noted above cannot be regarded as a satisfactory basis
for the application of this method on a large scale in stock-breeding farms, it is
probable that in this series the safety factor has been over-stressed by the ad-
ministration of large doses of serum and, while the results confirm the fact that