Immunisation

The further study of the pathogenetic powers of any particular bacterium involves the active immunisation of one or more previously normal animals. This end may be attained by various means; but it must be remembered that immunisation is not carried out by any hard and fast rule or by one method alone, but usually by a combination of methods adapted to the exigencies of each particular case. The ordinary methods include:

A. Active Immunisation.

I. By inoculation with dead bacteria (i. e., bacteria killed by heat; the action of ultra-violet rays, of chemical germicides, or by autolysis).

II. By the inoculation of attenuated strains of bacteria.

III. By the inoculation of living virulent bacteria (exalted in virulence if necessary).

B. Combined Active and Passive Immunisation:

IV. By the inoculation of toxin-antitoxin mixtures.