PREVENTIVE INOCULATION 75 
On the other hand, it must be recorded in contradiction 
to the favourable views so far expressed that those prac- 
titioners with whom I have discussed the matter have 
mostly been sceptical and antagonistic to the use of any 
anti-distemper vaccines, dubbing them all as uncertain 
in their action, and sometimes even dangerous. 
Based on the results of the experiments of these 
previously mentioned observers, bacterins containing 
B. bronchiseplicus are now listed by several reputable 
commercial houses. As regards the “preventive” use 
of the preparation, failures may be explained on the 
ground that it is still practically in the experimental 
stage, and there seems reason to believe that improved 
methods of preparation, as well as a more satisfactory 
technique of administration, will ensure better results in 
the future. 
Often the dogs are exposed too soon after treatment, 
and as their resistance has been lowered as a result of 
the introduction of antigen, they are more liable to 
infection than a normal dog under the same conditions. 
Perhaps in some cases the doses are too large, and in 
others too small; these questions can only be answered 
by experience. In Ferry’s last letter to me he said: 
“ As regards the efficacy of the vaccine as a prophylactic 
agent we have practically come to the conclusion that 
our dose is altogether too small, and that is the reason 
more favourable results have not been obtained. As 
pioneers in this line, perhaps we have been too con- 
servative. We have carried on enough well-controlled 
experiments to know that a vaccine composed of 
B. bronchisepticus will protect against distemper, and we 
have had numerous reports from outside to that same 
effect ; but we feel that the vaccine has not been doing 
itself justice, and that larger doses will improve it. To 
condemn the specificity of the organism on an unfavour- 
