75028319.htm

It will be seen from this table that vaccine I in a two-fold dilution completely
removed the bactericidal action of the serum, while in a three-fold dilution it failed
to do so. We may, therefore, for purposes of calculation hereafter take it that
" neutralisation " between receptor of vaccine and amboceptor of serum would be
obtained when a dilution of 2.5 of vaccine was added in equal parts to the serum.
on the other hand, the neutralisation point in the case of vaccine II and the
serum would be obtained in a 5.5-fold dilution. Thus we see that, as regards
receptor content, vaccine I stands in relation to vaccine II as 2.5 to 5.5, or as
1: 2.2. In other words, vaccine 11 is 21 times 'stronger' in immunising elements
than vaccine I.

12th May 1905.	Experiment II.	Serum of goat V.
Dilution of vaccine.	Vaccine I.	Vaccine II.
Undiluted	Growth.	Growth.
2-fold dilution	Sterile.	,,
3 ,, ,,	,,	,,
4 ,, ,,	,,	Sterile.
5 ,, ,,	,,	,,
6 ,, ,,	,,	,,
7 ,, ,,	,,	,,
8 ,, ,,	,,	,,
9 ,, ,,	,,	,,
10 ,, ,,	,,	,,

In this experiment the serum was evidently richer in amboceptor
content than was the case in the previous observation. Thus, the neutra-
lisation point in the case of vaccine I would be obtained in 1.5-fold dilution
and with vaccine II in a 3.5-fold dilution. Thus, the relation of their receptor
contents would be as r5 to 3.5, or as 1: 2.3. In other words, vaccine II