INOCULATION WITH DILUTED VIRUS. 
109 
amount of virus needed is many times less than with other 
methods. Certain disadvantages will doubtless he revealed by 
the experiments of the future, blit their importance cannot be 
foretold. 
I should not be surprised if greater advances are made by the 
investigations of the future, for the prevention of contagious 
diseases, than have been accomplished in the past; possibly vac*, 
cination in all forms may he discarded, but at present the ques¬ 
tion is fairly before the medical profession—Shall we vaccinate 
with a large number of comparatively inactive germs, or with a 
small number of those which retain their greatest virulence ? 
The solution of such a question can hardly be made from 
theoretical considerations; it may even require investigations 
which include a large number of individuals, scattered over a 
considerable territory and embracing a variety of diseases ; but, 
with the principles upon which these methods depend for their 
success once understood by our scientists, it cannot he long before 
we have the elements for a complete and satisfactory conclusion. 
At the same time it is not to be forgotten that the method 
by dilution, because of the little time required to prepare the 
virus, might often he resorted to when the other would he im¬ 
possible. 
In conclusion, I would call attention to the following points 
of this communication, which are believed to be original: 
First .—The method of producing a virus of standard 
strength. 
Second .—The fact that germs which usually multiply through¬ 
out the whole body may he compelled to limit their repro¬ 
duction to the point of inoculation by reducing the number in¬ 
serted. 
Third .—That this local multiplication grants an immunity 
from the disease in the future. 
4 
Fourth .—That a very small number of germs may be intro¬ 
duced into the tissues with impunity, and are not able to produce 
the least effect, either general or local. 
